Practice Test


1) Which of the cells is easily damaged by the short circuiting ?


2) The current capacity of a secondary cell is independent of :


3) E.M.F. of cell depends upon:


4) Cells are joined in parallel to get maximum current when:


5) Cells are joined in series to get maximum current when :


6) Side-wire bridge is an application of :


7) Two batteries of different e.m.f. and internal resistance are connected in series with an external resistor and current in circuit is 3 A. When polarity of one is reversed the current is 1 A. The ratio of their e.m.f.'s is :


8) A piece of a wire is cut into four equal parts and the pieces are bundled together closely to form a thicker wire. Compared with that of the original, the resistance of thicker wire is :


9) A wire stretched to increase its length by 10 %. What is the percentage increase in resistance ?


10) External resistance of a circuit is R which is connected to n exactly similar cells. If the current in the circuit is the same whether the cells are in series or in parallel, the value of internal resistance of each cell is :


11) 12 cells each having same e.m.f. are connected in series and are kept in a closed box. Some of them are wrongly connected. Two identical cells are connected in series to aid this battery and the current is 3 A when circuit is completed through an external resistance. The current is 2 A if the cells are made to oppose the battery through same resistance. The number of cells wrongly connected are:


12) Kirchhoff's second law is based on the law of conservation of :


13) For uniform wires with following dimensions, the resistance is least for:


14) The terminal potential difference of a battery exceeds its e.m.f. when it is connected :


15) The conductivity of super-conductor is :


16) The resistance of a discharge tube is :


17) A man wants to test his ammeter whose range is 0-1 ampere. He connects it to a 12 V storage battery and a carbon resistance of 48 ohm 0.5 watt. Which of the following is most likely to happen ?


18) A moving coil voltmeter is being used for measuring P.D. across a resistor of resistance r in which a current I is flowing. The voltmeter has a resistance R. The voltmeter will measure the P.D. more correctly as :


19) An electric current of 5 A is divided into three branches forming parallel combination. The length of wire in the three branches are in the ratio 2:3:4 while their diameters are in the ratio 3:4:5. Find the current in each branch if wires are of the same material.


20) 36 cells each of internal resistance 0.5 W and e.m.f. 1.5 V each are used to send current through an external circuit of 2 W resistance. Find the best mode of grouping them and current through external circuit.


21) n identical cells, each e.m.f. E and internal resistance r, are joined in series to form a closed circuit. The potential difference across any one of the cell is :


22) The current in a copper wire is increased by increasing the potential difference between its ends. Which of the following statements regarding n, the number of charge carries per unit volume in the wire and v, the drift velocity of the charge carries is correct ?


23) A piece of a wire is cut into four parts and the pieces are bundled together side by side to form a thick wire. Compared with that of the original wire, the resistance of the bundle is :


24) N identical cells, each e.m.f. E and internal resistance r, are joined in series to form 'a' closed circuit. One cell A is joined with the reverse polarity. The potential difference across each cell except A is :


25) The masses of three wires of copper are in the ratio 1:3:5 and their lengths are in ratio 5:3:1. The ratio of their electrical resistances is :


26) The momentum acquired by the electrons in length l of wire a current I starts to flow is :


27) A current I flows in a wire of circular cross-section with the free electrons traveling with a drift velocity v. The drift velocity of electrons when a current 2 I flows in another wire of twice the radius and of the same material is :


28) One meter long metallic wire is broken into two unequal parts P and Q. The part P is uniformly extended into another wire R. Length of R is twice the length of P and the resistance of R is equal to that of Q. The ratio of the resistances of P and R is :


29) Two voltmeters P and Q give the same reading when connected across a resistor X in a current - carrying circuit. But when connected across another resistor Y, the reading comes much lower in P than in Q. If P, Q, X, Y represent the respective resistance, the data shows that :


30) Two conductors, made of the same material, have lengths L and 2L, but have equal resistances. The two are connected in series in a circuit in which current is flowing. Which of the following is/are correct ?


31) If an electric current is passed through nerves the man :


32) n identical cells are joined in series with two cells A and B with reversed polarities e.m.f. of each cell is E and internal resistance is r. Potential difference across cell A or B is (n > 4):


33) An ammeter with internal resistance 90 ohm reads 1.85 A when connected in a circuit containing a battery and two resistances of 700 ohm and 410 ohm in series. Actual current will be :


34) Is it possible that any battery has some constant value of e.m.f. but the potential difference between the plates is zero ?


35) The infinity resistance plug in post-office box has


36) If a copper wire is stretched to make it 0.1% longer, then the percentage change in resistance is approximately :


37) When a resistance of 2 ohm is connected across the terminals of a cell, the current is 0.5 A. When the resistance is increased to 5 ohm, the current is 0.25 A. The e.m.f. of the cell is :


38) For a metallic wire, the ratio V/I ( V = applied potential difference, I = current flowing ) :


39) Given a current carrying wire of non-uniform cross-section. Which of the following is constant throughout the length of the wire ?


40) Dimensions of electric current is :


41) When a lamp is connected in series with a capacitor, then the lamp will :


42) The internal resistance of a cell is the resistance of :


43) Two cells when connected in series are balanced on 8 cm on a potentiometer. IF the cells are connected with polarities of one of the cell is reversed, they balance of 2 m. The ratio of e.m.f.'s of the two cells is :


44) A steady current flows in a metallic conductor of non-uniform cross-section. Which of the following quantity is constant along the conductor ?


45) Potential difference across the terminals of a battery is 50 V, when 11 A current is drawn. And it is 60 V, 1 A current is drawn. The e.m.f. and internal resistance of battery is :


46) The drift velocity does not depend upon :


47) If the radius of the copper wire carrying a current is doubled, the drift velocity of the electrons will :


48) The electrical conductivity of metal decreases with temperature because :


49) A number of 100 volt lamps connected in parallel are fed by a 130 V battery having an internal resistance of 2.6 ohm. If the resistance of each lamp is 200 ohm and the resistance of conducting wires is 0.40 ohm, the number of lamps which the battery can light properly is :


50) A battery of e.m.f. 10 V and internal resistance 0.5 ohm is connected across a variable resistance R. The value of R for which the power delivered in it is maximum is given by :


51) To convert a galvanometer into voltmeter we must connect a :


52) The resistance of a conductor increases with :


53) When a wire of resistance R is stretched and its radius becomes r/2, then new resistance will be :


54) Kirchhoff's first law is based on the law of conversation of :


55) A wire resistance R is stretched till its radius is half of the original value. Then the resistance of the stretched wire is :


56) The drift velocity of free electrons in a conductor is v when a current i is flowing in it. If both the radius and current are doubled, then drift velocity will be :


57) Which of the following has the largest resistance ?


58) The resistivity of metal increases with increase in temperature because :


59) A cell of e.m.f. has a resistance R connected across it, and a voltmeter measures the potential difference across the terminals of the cell as V. The internal resistance of the cell is :


60) Ohm's law is not obeyed by :


61) Express which of the following set up can be used to verify Ohm's law ?


62) In a Wheatstone's bridge, all the four arms have equal resistance R. IF the resistance of the galvanometer arm is also R, the equivalent resistance of the combination as seen by the battery is :


63) A cell e.m.f. E is connected across a resistance r. The potential difference between the terminals of the cell is found to be V. The internal resistance of the cell must be :


64) n cells of each e.m.f. E and internal resistance r send the same current through an external resistance R whether the cells are connected in series or in parallel. Then :


65) Two wires of the same material and the same length are connected to the two gaps of a meter bridge. The balancing length measured from left is 25 cm. The ratio of radius of the wire in the left gap to that in the right gap is :


66) When a current is divided between two resistors according to Kirchhoff's law, then the heat produced is :


67) The electric resistance of a certain wire of iron is R. If its length and radius both doubled, then its


68) Resistance n each of r ohm, when connected in parallel combination, give an equivalent resistance of R. If these resistances are connected in series, then the new combination would have a resistance equal to :


69) Current provided by a battery is maximum when :


70) Which of the following has negative temperature coefficient of resistance ?


71) For measuring the voltage of any circuit, the potentiometer is preferred to the voltmeter because :


72) In order to pass 10 % of main current through a moving coil galvanometer of 99 ohm, the resistance of the required shunt is :


73) A cell of negligible resistance and e.m.f. 2 volt is connected to series combination of 2, 3 and 5 ohm. The P.D. in volt between the terminals of 3 ohm resistance will be :


74) A wire is wound in the form of a solenoid or length l and diameter d. When a strong current is passed through the solenoid, there is tendency to :


75) The length of the wire is doubled. Its conductance will be :


76) When a wire of uniform cross-section a, length l and resistance R is bent into complete circle, resistance between any two diametrically opposite points will be :


77) The dimensions of electrical resistance are:


78) To draw maximum current from a combination of cells, how should the cells be grouped ?


79) A wire is cut into 4 pieces, which are put together by sides so obtain one conductor. If the original resistance of wire was R, the resistance of the bundle will be :


80) Ohm's law is true :


81) A voltmeter has a resistance of G ohm and range V volt. The value of resistance used in series to convert it into a voltmeter of range nV volt is :


82) Two bulbs of equal wattage, one having carbon filament and the other having a tungsten filament are connected in series to the mains, then :


83) Dimensions of resistance in an electrical circuit, in terms of dimensions of mass M, of length L, of time T and of current I, would be :


84) A galvanometer acting as a voltmeter will have :


85) A wire with a certain material is stretched slowly by ten per cent. Its new resistance and specific resistance becomes respectively :


86) A galvanometer has a coil of resistance 100 ohm and gives a full scale deflection for 30 m A current. If it is to work as a voltmeter of 30 volt range, the resistance required to be added will be :


87) Consider following statements :
(1) Kirchhoff's junction law follows from the conservation of charge.
(2) Kirchoff's loop law from the conservation of energy.
Which of the following is correct ?


88) Two wires A and B are made of copper. Both wires are 1 meter long but wire A is 1 mm thick and wire B is 2 mm thick. The specific resistance is :


89) When a potential difference V is applied across a conductor at temperature T, the drift velocity of electron is proportional to :


90) When a potential difference V is applied across a conductor at temperature T, the thermal speed of electron is proportional to :


91) The non ohmic device which exhibits a region of negative resistance is :


92) An electric bulb has a rating of 500 W, 100 V. It is used a circuit having a 200 V supply. What resistance must be connected in series with the bulb so that it delivers 500 W ?


93) For accurate measurements, the resistance of a voltmeter should be


94) The resistance of a straight conductor does not depend on its


95) In a potentiometer arrangement, a cell 1.25 V gives a balance point at 35 cm length of the wire. If the cell is replaced by another cell and the balance point shifts to 63 cm the emf of the second cell is


96) Given n resistors, combine them to get maximum and minimum resistance. The ratio of maximum to minimum resistance is


97) If the combination is connected to a 20 V battery, then current drawn from the battery is


98) A copper wire is stretched to make it 0.1% longer. The percentage increase in resistance will be


99) How many electrons per second constitute a current of one micro ampere?


100) A piece of copper and a piece of germanium are cooled from the room temperature down to 77 K.


101) The capacity of a storage cell is 5 ampere hour. The maximum current it can supply for one hour is


102) An electric cell does 5 joule of work in carrying 10 C of charge around a closed electric circuit. The electromotive force of the cell is


103) A steady current flows in a metallic conductor of non-uniform cross-section. The quantity/quantities constant along the length of the conductor is/are


104) Potential difference of a cell in an open circuit is 6 volt but it falls to 4 volt when a current of 2 A is drawn from it. The internal resistance of the cell is


105) We are able to obtain fairly large currents in a conductor because


106) A piece of wire is cut into four equal parts and the piece are bundled together side by side to form a thick wire. Compared with that of the original wire, the resistance of the bundle is


107) Statement 1 : Potential difference V is applied across a copper wire of diameter d and length L. When the diameter of the wire is doubled keeping the other parameters same, the drift speed of the electrons remains unchanged.
Statement 2 : Current density remains the same here.


108) Statement 1 : An electrical bulb starts glowing instantly as it is switched on.
Statement 2 : Drift speed of electrons in a metallic wire is very large for metallic conductors.


109) A wire is carrying 2 A current from left to right. Drift speed of electron in conductors is 1 mm/s. A person is moving towards right with 1 mm/s velocity parallel to conductor. Average velocity of electron with respect to this person.


110) Current through above conductor with respect to moving person


111) A galvanometer of resistance 98 ohms is shunted by a resistance of 2 ohms. The fraction of the total current that pass through is


112) The potential difference between the terminals of a cell is open circuit is 2.2 volt. With resistance of 5 ohm across the terminals of a cell, the terminal potential difference is 1.8 volt. The internal resistance of the cell is


113) Copper and germanium are both cooled to 70 K from room temperature, then


114) A Daniel cell is balanced on 125 cm length of a potentiometer wire. Now the cell is short-circuited by a resistance of 2 ohm and the balance is obtained at 100 cm. The internal resistance of the Daniel cell is


115) Consider four circuits shown in the figure below. In which circuit power dissipated is greatest? (Neglect the internal resistance of the power supply)


116) Statement 1 : 10 identical bulbs are connected in series. If one of the bulb gets fused and the remaining 9 bulbs are reconnected across the same supply in series then, light gets increased in the room.
Statement 2 : The power consumption by 9 bulbs is more than the 10 bulbs.


117) Statement 1 : Current is passed through a metallic wire, heating it red. When cold water is poured on half of its portion then rest of the half portion becomes more hot.
Statement 2 : Resistance decreases due to decreases in temperature and so current through wire increases.


118) What is the emf of cell used in experiment?


119) What is the maximum current that can be withdraw from cell?


120) What is the maximum power can be with draw from cell?


121) If an increase in length of copper wire is 0.5% due to stretching, the percentage increase in its resistance will be


122) A battery of emf E and internal resistance r is connected to an external resistance R the condition for maximum power transfer is


123) A resistor has a colour code of green, blue, brown and silver. What is its resistance?


124) A battery having e.m.f. 5V and internal resistance 0.5 Ω is connected with a resistance of 4.5 Ω then the voltage at the terminals of battery is


125) The length of a conductor is doubled and its radius is halved, its specific resistance is


126) In India electricity is supplied for domestic use at 220 V. It is supplied at 110 V in USA. If the resistance of a 60 W bulb for use in India is R, the resistance of a 60 W bulb for use in USA will be


127) The chemical equivalent of silver is 108. If the current in a silver voltmeter is 2 amp, the time required to deposit 27 grams of silver will be


128) Which of the following set up can be used to verify the Ohm’s law?


129) Two wires of the same material and equal length are joined in parallel combination. If one of them has half the thickness of the other and the thinner wire has a resistance of 8 ohms, the resistance of the combination is equal to


130) If the temperature of cold junction of thermocouple is lowered, then the neutral temperature


131) Which of the following statements is correct?


132) Two electric bulbs, one of 200 volt 40 watt and the other 200 volt 100 watt are connected in a house wiring circuit


133) An electric current passes through a circuit containing two wires of the same material connected in parallel. If the lengths of the wires are in the ratio of 4/3 and radius of the wires are in the ratio of 2/3, then the ratio of the current passing through the wires will be


134) A 100 watt bulb working on 200 volt and a 200 watt bulb working on 100 volt have


135) With the rise of temperature the resistivity of a semiconductor


136) A battery consists of a variable number 'n' of identical cells having internal resistances connected in series. The terminals of battery are short circuited and the current i is measured. Which of the graph below slows the relationship between i and n?


137) Which of the following circuits is correct for verification of Ohm’s law?


138) If 2.2 kilowatt power is transmitted through a 10 ohm line at 22000 volt, the power loss in the form of heat will be


139) Masses of the three wires of same material are in the ratio of 1:2:3 and their lengths in the ratio of 3:2:1. Electrical resistance of these wires will be in the ratio of


140) A galvanometer can be converted into a voltmeter by connecting


141) Two conductors of the same material have their diameters in the ratio 1 : 2 and their lengths in the ratio 2 : 1. If the temperature difference between their ends is the same, then the ratio of amounts of heat conducted per second through them will be


142) A railway compartment is lit up by thirteen lamps each taking 2.1 A at 15 V. The heat generated per second in each lamp will be


143) Potential gradient is defined as


144) By using only two resistances coils-singly, in series or in parallel one should be able to obtain resistance of 3,4,12 and 16 ohm. The separate resistance of the coil are


145) There are two electric bulbs of 40 W and 100 W. Which one will be brighter when first connected in series and then in parallel


146) The reciprocal of resistance is


147) The accurate measurement of emf can be obtained using


148) A current of 2 A passing through conductor produces 80 J of heat in 10 seconds. The resistance of the conductor is


149) In a copper voltmeter , if the current (I) and time (t) variations of the type as shown in figure, the mass deposited in 30 min is [Atomic weight of copper is 63.5 and Faraday constant is 96500 C per g equivalent]


150) The graph between resistivity and temperature, for a limited range of temperatures, is a straight line for a material like


151) A house wife uses a 100 W bulb 8 h a day , and an electric heater of 300 W for 4 h a day. The total cost for the month of June at the rate of 0.05 rupee per unit will be


152) Two cells, each of e.m.f.E and internal resistance r are connected in parallel between the resistance R. The maximum energy given to the resistor will be, only when


153) An electric bulb is rated 60 W, 220 V. The resistance of its filament is


154) The tolerance level of a resistor with the colour code red, blue, orange, gold is


155) For a given thermocouple neutral temperature


156) A battery consists of a variable number (n) of identical cells, each having an internal resistance r connected in series. The terminal of the battery is short-circuited. A graph of current versus the number of cells will be as shown in figure


157) In a potentiometer of one metre length, an unknown e.m.f. voltage source is balanced at 60 cm length of potentiometer wire, while a 3 volt battery is balanced at 45 cm length. Then the e.m.f. of the unknown voltage source is


158) x g of Ag is deposited by passing 4 A of current of for 1 h. How many gram of Ag will be deposited by passing 6 A for 40 min?


159) Two bulbs 40 W and 60 W and rated voltage 240 V are connected in series across a potential difference of 420 V. Which bulb will work at above its rated voltages?


160) Two heater wires of equal length are first connected in series and then in parallel. The ratio of heat produced in the two cases is


161) When a piece of aluminium wire of finite length is drawn through a series of dies to reduce its diameter to half its original value, its resistance will become


162) Watt-hour meter measures


163) A potentiometer having the potential gradient of 2 mV/cm is used to measure the difference of potential across a resistance of 10 ohm. If a length of 50 cm of the potentiometer wire is required to get the null point, the current passing through the 10 ohm resistor is (in mA)


164) Two electric lamps of 40 watt each are connected in parallel. The power consumed by the combination will be


165) Which arrangement of four identical resistance should be used to draw maximum energy from a cell of voltage V?


166) An electric fan and a heater are marked as 100 watt, 220 volt and 1000watt, 220 volt respectively. The resistance of the heater is


167) 5 ampere of current is passed through a metallic conductor. The charge flowing in one minute in coulomb will be


168) The length of the wire is doubled. Its conductance will be


169) A student has 10 resistors of resistance 'r'. The minimum resistance made by him from given resistors is


170) Which of the following relation is wrong?


171) An ammeter reads 0.90 A when connected in series with a silver voltmeter that deposits 2.60 g of silver in 40 min. By what percentage is the ammeter reading is correct? Atomic weight of silver = 108 and 1 F = 96500 C?


172) The following four wires are made of the same material and are at the same temperature. Which one of them has the highest electrical resistance?


173) Two different metals are joined end to end. One end is kept at constant temperature and the other end is heated to a very high temperature. The high depicting the thermo e.m.f. is


174) Which statement is true?
(i) Kirchoff’s law is equally applicable to both AC and DC.
(ii) Semiconductors have a positive temperature coefficient of resistance.
(iii) Meter bridge is greater sensitive when the resistance of all four arms of the bridge is of the same order.
(iv) The emf of a cell depends upon the size and area of electrodes.


175) An electric iron draws 5 amp a TV set draws 3 amp and refrigerator graws 2 amp from a 220 volt main line. The three appliances are connected in parallel. If all the three are operating at the same time, the fuse used may be of


176) There are three resistance coils of equal resistance. The maximum number of resistances you can obtain by connecting them in any manner you choose, being free to use any number of the coils in any way is


177) To get the maximum current from a parallel combination of n identical cells each of internal resistance r and external resistance R, when


178) The resistance of a discharge tube is


179) In an electroplating experiment, m gm of silver is deposited when 4 ampere of current flows for 2 minute. The amount (in gm) of silver deposited by 6 ampere of current for 40 second will be


180) For which of the following the resistance decreases on increasing the temperature


181) Current flows through a metabolic conductor whose area of cross-section increases in the direction of the current. If we move in this direction,


182) The resistance of a metal increases with increasing temperature because


183) By mistake a voltmeter is connected in series and an ammeter is connected in parallel with a resistance in an electrical circuit. What will happen to the instrument?


184) The electric intensity E, current density j and specific resistance k are related to each other by the relation


185) The same mass of copper is drawn into two wires 1 mm and 2 mm thick. Two wires are connected in series and current is passed through them. Heat produced in the wire is in the ratio


186) Resistance in the two gaps of a meter bridge are 10 ohm and 30 ohm respectively. If the resistances are interchanged the balance point shifts by


187) An electric bulb rated 220 V, 100 W is connected in series with another bulb rated 220 V, 60 W. If the voltage across the combination is 220 V, the power consumed by the 100 W bulb will be about


188) It is easier to start a car engine on a hot day than on a cold day. This is because the internal resistance of the car battery


189) An electric lamp is marked 60 W,230 V. The cost of a 1 kWh of energy is Rs.1.25. The cost of using this lamp 8 hrs a day for 30 days is


190) Two resistances R and 2R are connected in parallel in an electric circuit. The thermal energy developed in R and 2R are in the ratio


191) An electric bulb is rated 220 V – 100 W. The power consumed by it when operated on 110 V will be


192) Two wires of the same material but of different diameters carry the same current i. If ratio of their diameters is 1:2, then the corresponding ratio of their mean drift velocities will be


193) The net resistance of a voltmeter should be large to ensure that


194) The maximum current that flows through a fuse wire before it blows out varies with its radius as


195) Four wires AB, BC, CD, DA of resistance 4 ohm each and a fifth wire BD of resistance 8ohm are joined to form a rectangle ABCD of which BD is a diagonal. The effective resistance between the points A and B is


196) To deposit one litre of hydrogen at 22.4 atmosphere from acidulated water, the quantity of electricity that must pass through is


197) A 25 W, 220 V bulb and a 100 W, 220 V bulb are connected in parallel across a 440 V line


198) An electric bulb of 100 watt is connected to a supply of electricity of 220 V. Resistance of the filament is


199) Which of the following is not a correct statement?


200) According to Faraday’s law of electrolysis, the amount of decomposition is proportional to


201) A 100 ohm galvanometer gives full scale deflection at 10 mA. How much shunt is required to read 100 mA?


202) The steady current flows in a metallic conductor of non-uniform cross-section. The quantity/quantities constant along the length of the conductor is/are


203) There are 8 equal resistance R. Two are connected in parallel, such four groups are connected in series, the total resistance of the system will be


204) Two electric bulbs whose resistances are in the ratio of 1∶2 are connected in parallel to a constant voltage source. The powers dissipated in them have the ratio


205) Some electric bulbs are connected in series across a 220V supply in a room. If one bulb is fused, then remaining bulbs are connected again in series across the same supply. The illumination in the room will be


206) A wire is broken in four equal parts. A packet is formed by keeping the four wires together. The resistance of the packet in comparison to the resistance of the wire will be


207) Sensitivity of potentiometer can be increased by


208) A wire is stretched so as to change its diameter by 0.25%. The percentage change in resistance is


209) A metallic resistor is connected across a battery. If the number of collisions of the free electrons with the lattice is some how decreased in the resistor (for example by cooling it), the current will


210) The negative Zn pole of Daniell cell, sending a constant current through a circuit, decreases in mass by 0.13 g in 30 min. If the electrochemical equivalent of Zn and Cu are 32.5 and 31.5 respectively, the increase in the mass of the positive Cu pole in this time is


211) Consider four circuits shown in figure. In which circuit power dissipated is greatest. (Neglect the internal resistance of the power supply)


212) A source of emf E=15V and having negligible internal resistance, is connected to a variable resistance, so that the current in the circuit increases with time as I=1.2t+3. Then, the total charge that will flow in first 5s will be


213) Two bulbs, one of 50 watt and another of 25 watt are connected in series to the mains. The ratio of the currents through them is


214) A wire of a certain material is stretched slowly by ten percent. Its new resistance and specific resistance become respectively


215) Three electric bulbs of rating 60 W each are joined in series and then connected to electric mains. The power consumed by these three bulbs will be


216) In a meter bridge experiment, the ratio of the left gap resistance to right gap resistance is 2:3, the balance point from left is


217) A battery is charged at a potential of 15 V in 8 hours when the current flowing is 10 A. The battery on discharge supplies a current of 5 A for 15 hours. The mean terminal voltage during discharge is 14 V. The "Watt-hour" efficiency of battery is


218) The number of dry cells, each of e.m.f. 1.5 volt and internal resistance 0.5 ohm that must be joined in series with a resistance of 20 ohm so as to send a current of 0.6 ampere through the circuit is


219) Kirchoff’s second law for the analysis of circuit is based on


220) When a current passes through the junction of two different metals, evolution or absorption of heat at the junction is known as


221) On passing the current in water voltmeter, hydrogen


222) A certain current passing through a galvanometer produces a deflection of 100 divisions. When a shunt of one ohm is connected, the deflection reduces to 1 division. The galvanometer resistance is


223) For measurement of potential difference, potentiometer is preferred in comparison to voltmeter because


224) Two identical conductors maintained at same temperatures are given potential differences in the ratio 1:2. Then the ratio of their drift velocities is


225) The mass of ions deposited during a given interval of time in the process of electrolysis depends on


226) A cell of emf 6 V and resistance 0.5 ohm is short circuited. The current in the cell is


227) What is the resistance of a carbon resistance which has bands of colours brown, black and brown


228) The chemical equivalent of copper and zinc are 32 and 108 respectively. When copper and silver voltmeters are connected in series and electric current is passed through for sometime, 1.6 g of copper is deposited. Then, the mass of silver deposited will be


229) A Copper wire of length 1 m and radius 1 mm is joined in series with an iron wire of length 2 m and radius 3 mm and a current is passed through the wires. The ratio of the current density in the wires. The ratio of the current density in the copper and iron wires is


230) To draw maximum current from a combination of cells, how should the cells be grouped?


231) An electric wire of length 'L' and area of cross-section a has resistance R ohm. Another wire of the same material having same length and area of cross-section 4a has a resistance of


232) When a current flows through a conductor its temperature


233) A house, served by 220 V supply line, is protected by a 9 A fuse. The maximum number of 60W bulbs in parallel that can be turned on is


234) Same current is being passed through a copper voltmeter and a silver voltmeter. The rate of increase in weights of the cathode of the two voltmeters will be proportional to


235) Two resistances R and 2 R are connected in parallel in an electric circuit. The thermal energy developed in in R and 2 R is in the ratio


236) 3 identical bulbs are connected in series and these together dissipate a power P. If now the bulbs are connected in parallel, then the power dissipated will be


237) How much current should be passed through a silver voltmeter to deposit 200 gm of silver per hour on the cathode? (Faraday constant = 96500 C/mol and relative atomic mass of silver is 108)


238) Which of the following graphs shows the variation of thermoelectric power with temperature difference between hot and cold junction in thermocouples?


239) A given resistor has the following colour scheme of the various strips on it, brown, black, green and silver. Its value in ohm is


240) A straight conductor of uniform cross-section carries a current i, If s is the specific charge of an electron, the momentum of all the free electrons per unit length of the conductor, due to their drift velocity only is


241) Two cells A and B are connected in the secondary circuit of a potentiometer one at a time and the balancing length are respectively 400 cm and 440 cm. The emf of the cell A is 1.08V. The emf of the second cell B is volt is


242) In a potentiometer circuit there is a cell of e.m.f. 2 volt, a resistance of 5 ohm and a wire of uniform thickness of length 1000 cm and resistance 15 ohm. The potential gradient in the wire is


243) A galvanometer has a resistance of 25 ohm and a maximum of 0.01 A current can be passed through it. In order to change it into an ammeter of range 10 A, the shunt resistance required is


244) The resistance of hot tungsten filament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 lamps, when not in use?


245) A strip of copper and another of germanium are cooled from room temperature to 80 K. The resistance of


246) Flash light equipped with a new set of batteries, produces bright white light. As the batteries wear out


247) A potentiometer has uniform potential gradient across it. Two cells connected in series (i) to support each other and (ii) to oppose each other are balanced over 6m and 2m respectively on the potentiometer wire. The e.m.f.'s of the cells are in the ratio of


248) To convert a moving a coil galvanometer (MCG) into a voltmeter


249) For a given temperature difference which of the following pairs will generate maximum thermo-emf?


250) The variation between V-i has been shown by V-i graph for heater filament.


251) A copper voltmeter and a silver voltmeter are connected in series in a circuit. The rate of the increase in the weight of the cathode in the two voltmeters will be in the ratio of


252) Constantan wire is used in making standard resistances because its


253) In ballistic galvanometer, the frame in which the coil is wound is non-metallic to


254) The resistance of an ideal voltmeter is


255) When an electric heater is switched on, the current flowing through it (i) is plotted against time (t). Taking into account the variation of resistance with temperature, which of the following best represents the resulting curve


256) If an electric current is passed through a nerve of a man, then man


257) A meter bridge is used to determine the resistance of an unknown wire by measuring the balance point length l. If the wire is replaced by another wire of same material but with double the length and half the thickness, the balancing point is expected to be


258) All of the following statements are true except


259) Two wires that are made up of two different materials whose specific resistance are in the ratio 2 : 3, length 3 : 4 and area 4 : 5. The ratio of their resistances is


260) If a steady current of 100 A is passed then how much time is taken to deposit 0.254 kg of copper on the cathode of copper voltmeter. Use the known value of Faraday constant and relative atomic mass of copper is 63.5.


261) Two electric bulbs (60W and 100W respectively) are connected in series. The current passing through them is


262) Heat produced in a wire of resistance R due to current flowing at constant potential difference is proportional to


263) The resistance of a wire is 20 ohm. It is so stretched that the length becomes three times, then the new resistance of the wire will be


264) If a wire is stretched to make it 0.1% longer, its resistance will


265) Two electric bulbs, each designed to operate with a power of 500 W in 220 V line are connected in series in a 110 V line. The power generated by each bulb will be


266) Two uniform wires A and B are of the same metal and have equal masses. The radius of wire A is twice that of wire B.The total resistance of A and B when connected in parallel is


267) The colour sequence in a carbon resistor is red, brown, orange and silver. The resistance of the resistor is


268) In the absence of applied potential, the electric current flowing through a metallic wire is zero because


269) A bulb of 220 V and 300 W is connected across 110 V circuit. The percentage reduction in power is


270) By a cell a current of 0.9 A flows through 2 ohm resistor and 0.3 A through 7 ohm resistor. The internal resistance of the cell is


271) In Wheatstone’s bridge P = 9 ohm, Q = 11 ohm,R = 4 ohm and S = 6 ohm. How much resistance must be put in parallel to the resistance S to balance the bridge?


272) The resistivity of a wire depends on its


273) A storage cell is charged by 5 amp D.C. for 18 hours. Its strength after charging will be


274) In a galvanometer 5% of the total current in the circuit passes through it. If the resistance of the galvanometer is G, the shunt resistance S connected to the galvanometer is


275) An electric lamp is marked 60 W, 230 V. The cost of kilowatt hour of power is Rs. 1.25. The cost of using this lamp 8 hrs a day for 30 days is


276) A 200 W and a 100 W bulb, both meant for operation at 220 V are connected in series. When connected to a 220 V supply the power consumed by the combination is


277) A cell of emf E is connected across a resistance R the potential difference between the terminals of the cell is found to be V volt. Then the internal resistance of the cell must be


278) Two copper wires have their masses in the ratio 2 : 3 and the lengths in the ratio 3 : 4 the ratio of their resistance is


279) Two bulbs of 100 W and 200 W working at 220 V are joined in series with 220 V supply. Total power consumed will be


280) A cell in secondary circuit gives null deflection for 2.5 m length of potentiometer having 10 m length of wire. If the length of the potentiometer wire is increased by 1 m without changing the cell in the primary, the position of the null point now is


281) The electromotive force of a primary cell is 2 volt. When it is short-circuited it gives a current of 4 ampere. Its internal resistance in ohm is


282) How many coulombs of electric charge must pass through acidulated water in order to release 22.4 L Of hydrogen at NTP?


283) If an ammeter is to be used in place of a voltmeter, then we must connect with the ammeter a


284) Heat produced (cals) in a resistance R when a current I amperes flows through it for t seconds is given by the expression


285) The electrolyte used in Lechlanche cell is


286) The relaxation time in conductors


287) An electric heater rated 220 V and 550 W is connected to AC mains. The current drawn by it is


288) An electric heater rated 220 V and 550 W is connected to AC mains. the resistance between the square faces is


289) Which of the adjoining graphs represents ohmic resistance?


290) A cylindrical conductor has uniform cross-section. Resistivity of its material increases linearly from left end to right end. If a constant current is flowing through it and at a section distance x from left end, magnitude of electric field intensity is E, which of the following graphs is correct?


291) How much energy in kilowatt hour is consumed in operating ten 50 watt bulbs for 10 hours per day in a month (30 days)


292) Ampere hour is the unit of


293) The equivalent resistance of resistor connected in series is always


294) Which of the following has a negative temperature coefficient?


295) The electric bulbs have tungsten filaments of same length. If one of then gives 60 watt and other 100 watt then


296) When an electrical appliance is switched on, it responds almost immediately, because


297) If voltage across a bulb rated 220 Volt - 100 Watt drops by 2.5% of its rated value, the percentage of the rated value by which the power would decrease is


298) If potential difference is applied, the drift velocity at temperature T is


299) In an electric heater 4 amp current passes for 1 minute at potential difference of 250 volt, the power of heater and energy consumed will be respectively


300) Which of the following characteristics of electron determines the current in a conductor?


301) For comparing the e.m.f.'s of two cells with a potentiometer, a standard cell is used to develop a potential gradient along the wires. Which of the following possibilities would make the experiment unsuccessful?


302) Three resistances each of 1 ohm, are joined in parallel. Three such combinations are put in series, then the resultant resistance will be


303) Two wires of the same material and having same uniform area of cross-section are connected in series in an electrical circuit. The masses of the wires are m and 2m. When a current I flows in the circuit, the heats produced by them in a given time are in ratio


304) A copper and a chromium voltmeter are connected in series with a battery. It found that in half an hour 0.475 g of copper and 0.130 g of chromium have been deposited. The ECE ratio of copper and chromium is


305) A 12 HP motor has to be operated 8 h/day. How much will it cost at the rate of 50 paise/kWh in 10 days?


306) Combination of two identical capacitors, a resistor R and a DC voltage source of voltage 6 V is used in an experiment onC-R circuit. It is found that for a parallel combination of the capacitor the time in which the voltage of the fully charged combination reduces to half its original voltage is 10s. For series combination the time needed for reducing the voltage of the fully charged series combination by half is


307) Two filaments of same length are connected first in series and then in parallel. For the same amount of main current flowing the ratio of the heat produced is


308) The resistance will be least in a wire with dimension


309) Three resistors are connected to form the sides of a triangle ABC, the resistance of the sides AB, BC and CA are 40 ohm, 60 ohm and 100 ohm respectively. The effective resistance between the points A and B in ohm will be


310) A potential difference is applied across the ends of a metallic wire. If the potential difference is doubled, the drift velocity will


311) A silver voltameter of resistance 2 ohm and a 3 ohm resistor are connected in series across a cell. If a resistance of 2 ohm is connected in parallel with the voltameter, then the rate of deposition of silver


312) A nichrome wire 50 cm long and one square millimetre cross-section carries a current of 4A when connected to a 2V battery. The resistivity of nichrome wire in ohm metre is


313) If an ammeter is connected in parallel to a circuit, it is likely to be damaged due to excess


314) A source of a primary cell is 2 V. What is the short circuited it provides 4 A current, then the internal resistance of cell will be


315) The current inside a copper voltameter


316) A thermocouple is formed by two metals X and Y, metal X comes earlier to Y in Seebeck series. If temperature of hot junction increases beyond the temperature of inversion, then direction of current in thermocouple will be from


317) In a meter bridge experiment, null point is obtained at 20 cm from one end of the wire when resistance X is balanced against another resistance Y. If X < Y, then where will be the new position of the null point from the same end, if one decides to, balance a resistance of 4X against Y?


318) In a potentiometer arrangement, a cell of emf 1.5V gives a balance point at 27cm length of wire. If the cell is replaced by another cell and balance point shifts to 54cm, the emf of the second cell is


319) By ammeter, which of the following can be measured


320) Constant current is flowing through a linear conductor of non-uniform area of cross-section. The charge flowing per second through the area of conductor at any cross-section is


321) Two wires of same material have length L and 2 L and cross-sectional areas 4 A and A respectively. The ratio of their specific resistances would be


322) n identical cells each of e.m.f. E and internal resistance r are connected in series. An external resistance R is connected in series to this combination. The current through R is


323) As the temperature of hot junction increases, the thermo e.m.f


324) One kilowatt hour is equal to


325) 2, 4 and 6 S are the conductance of three conductors. When they are joined in parallel, their equivalent conductance will be


326) What is immaterial for an electric fuse?


327) An electric bulb is rated 220 V - 100 W. The power consumed by it when operated on 110 V will be


328) The electron drift speed is small and the charge of the electron is also small but still, we obtain large current in a conductor. This is due to


329) The relation between Faraday’s constant F, electron charge e and avogadro number N is


330) A voltmeter has resistance of 2000 ohm and it can measure upto 2 V. If we want to increase its range to 10 V, then the required resistance in series will be


331) A potential difference V is applied to a copper wire of length l and thickness d. If V is doubled, the drift velocity


332) The maximum power dissipated in an external resistance R, when connected to a cell of emf E and internal resistance r, will be


333) A galvanometer acting as a voltmeter should have


334) With a potentiometer null point were obtained at 140 cm and 180 cm with cells of emf 1.1 V and one unknown X volt. Unknown emf is


335) In an experiment of meter bridge, a null point is obtained at the centre of the bridge wire. When a resistance of 10 ohm is connected in one gap, the value of resistance in other gap is


336) If an ammeter is joined in parallel through a circuit, it can be damaged due to excess


337) Two wires have resistances R and 2 R. When both are joining in series and in parallel, then ratio of heats generated in these situations on applying the same voltage, is


338) On increasing the temperature of a conductor, its resistance increases because the


339) A steady current of 5 amps is maintained for 45 mins. During this time it deposits 4.572 gm of zinc at the cathode of a voltmeter. E.C.E. of zinc is


340) How much current should be passed through acidified water for 100s to liberate 0.224 L of hydrogen?


341) A metal wire is subjected to a constant potential difference. When the temperature of the metal wire increases, the drift velocity of the electron in it


342) Three resistors each of 2 ohm are connected together in a triangular shape. The resistance between any two vertices will be


343) All the edges of a block with parallel faces are unequal. Its tangent edge is twice its shortest edge. The ratio of the maximum to minimum resistance between parallel faces is


344) A current of 16 ampere flows through molten NaCl for 10 minute. The amount of metallic sodium that appears at the negative electrode would be


345) Two rods of same material and length have their electric resistances in ratio 1 : 2. When both rods are dipped in water, the correct statement will be


346) 1 kg piece of copper is drawn into a wire 1 mm thick, and another piece into a wire 2 mm thick. Compare the resistance of these wires


347) Faraday’s 2nd law states that mass deposited on the electrode is directly proportional to


348) What is the volume of hydrogen liberated at NTP by the amount of charge which liberates 0.3175 g of copper?


349) A 60 watt bulb operates on 220 V supply. The current flowing through the bulb is


350) Consider a rectangular slab of length L and area of cross section A. A current I is passed through it. If the length is doubled, the potential drop across the end faces


351) A thick wire is stretched, so that its length become two times. Assuming that there is no change in its density, then what is the ratio of change in resistance of wire to the initial resistance of wire?


352) A heater of 220 V heats a volume of water in 5 min. The same heater when connected to 110 V heats the same volume of water in (minute)


353) A wire 100cm long and 2.0 mm diameter has a resistance of 0.7 ohm, the electrical resistivity of the material is


354) The potential gradient along the length of a uniform wire is 10 volt/metre. B and C are the two points at 30 cm and 60 cm point on a meter scale fitted along the wire. The potential difference between B and C will be


355) An electric bulb rated for 500 W at 100V is used in a circuit having a 200 V supply. The resistance R that must be put in series with the bulb, so that the bulb drawn 500 W is


356) The two bulbs, one of 60 W and other 200 W are connected in series to a 200 volt line, then


357) A capacitor is connected to a cell of emf E having some internal resistance r. The potential difference across the


358) Which of the following statements is wrong?


359) Two bulbs when connected in parallel to a source take 60 W each. The total power consumed when they are connected in series with the same source is


360) An electric heater kept in vacuum is heated continuously by passing electric current. Its temperature


361) There are n similar conductors each of resistance R. The resultant resistance comes out to be x when connected in parallel. If they are connected in series, the resistance comes out to be


362) The production of e.m.f. by maintaining a difference of temperature between the two junctions of two different metals is known as


363) Two identical heaters rated 220 volt,1000 watt are placed in series with each other across 220 volt lines. If resistance does not change with temperature, then the combined power is


364) When current flows through a conductor, then the order of drift velocity of electrons will be


365) n equal resistors are first connected in series and then connected in parallel. What is the ratio of the maximum to the minimum resistance


366) A heater coil is cut into two equal parts and only one part is now used in the heater. The heat generated will now be


367) In Cu-Fe couple, the flow of current at the temperature of inversion is


368) In voltaic air cell if 5g zinc is consumed, how many ampere hours shall we get?


369) When a metal conductor connected to the left gap of a meter bridge is heated, the balancing point


370) A wire of resistance R is elongated n- fold to make a new uniform wire. The resistance of new wire


371) When connected across the terminals of a cell, a voltmeter measures 5V and a connected ammeter measures 10 A of current. A resistance of 2 ohm is connected across the terminals of the cell. The current flowing through this resistance will be


372) Two wires 'A' and 'B' of the same material have their lengths in the ratio 1∶2 and radii in the ratio 2∶1. The two wires are connected in parallel across a battery. The ratio of the heat produced in 'A' to the heat produced in 'B' for the same time is


373) A solenoid is at potential difference of 60 V and current flowing through it is 15 ampere, then the resistance of coil will be


374) Five equal resistors when connected in series dissipated 5 W power. If they are connected in parallel, the power dissipated will be


375) A uniform wire of resistance R is uniformly compressed along its length, until its radius becomes n times the original radius. Now resistance of the wire becomes


376) Ohm's law is true


377) A wire has a resistance of 12 ohm. It is bent in the form of equilateral triangle. The effective resistance between any two corners of the triangle is


378) A battery is made by connecting 6 cells each having capacity 5 Ah at 1.5V. The battery will have capacity equal to


379) A given carbon resistor has the following colour code of the various strips: orange, red, yellow and gold. The value of resistance in ohm is


380) Twelve wires of equal resistance R are connected to form a cube. The effective resistance between two opposite diagonal ends will be


381) The maximum power drawn out of the cell from a source is given by (where r is internal resistance)


382) A galvanometer of resistance, G, is shunted by a resistance S ohm. To keep the main current in the circuit unchanged, the resistance to be put in series with the galvanometer is


383) A bulb of 220 V and 300 W is connected across 110 V circuit, the percentage reduction in power is


384) A voltmeter having a resistance of 998 ohm is connected to a cell of e.m.f. 2 volt and internal resistance 2 ohm. The error in the measurement of e.m.f. will be


385) Twelve cells, each having emf E volts are connected in series and kept in a closed box. Some of these cells are wrongly connected with positive and negative terminals reversed. This 12-cell battery is connected with an ammeter, an external resistance R ohm and a two-cell battery (two cells of the same type used earlier, connected perfectly in series). The current in the circuit when the 12-cell battery and 2-cell battery aid each other is 3A and 2A when they oppose each other. Then, the number of cell in 12-cell battery that are connected wrongly is


386) A bulb has specification of one kilowatt and 250 volts, the resistance of bulb is


387) The resistance of a wire is R. If the length of the wire is doubled by stretching, then the new resistance will be


388) Three resistances each of 4Ω are connected in the form of an equilateral triangle. The effective resistance between any two corners is


389) To deposit one gm equivalent of an element at an electrode, the quantity of electricity needed is


390) In a thermocouple, which of the following statements is not true


391) A voltmeter essentially consists of


392) The resistance of ideal voltmeter is


393) An energy source will supply a constant current into, the load, if its internal resistance is


394) In water voltmeter, the electrolysis of …… takes place


395) When a resistance of 2 ohm is connected across the terminals of a cell, the current is 0.5 ampere. When the resistance is increased to 5 ohm, the current is 0.25 ampere. The internal resistance of the cell is


396) The value of current required to deposit 0.972 gm of chromium in 3 hours if the E.C.E. of chromium is 0.00018 gm per coulomb, is


397) Peltier coefficient for the junction of a pair of metals is proportional to


398) A fuse wire of circuit cross-section and having diameter of 0.4 mm, allows 3 A of current to pass through it. But if another fuse wire of same material and circular cross-section and having diameter of 0.6 mm is taken, then the amount of current passed through the fuse is


399) Fifty electric bulbs, all identical, are connected in series across the mains of a 220 V supply. After one bulb is fused, the remaining 49 bulbs connected in series across the same mains. The illumination will be


400) The resistance of a cell does not depend on


401) Identify the incorrect statement regarding a superconducting wire


402) Under what condition will the strength of current in a wire of resistance R be the same for connection is n series or in parallel of n identical cells each of the internal resistance r, when


403) If three bulbs 60 W, 100 W and 200 W are connected in parallel, then


404) Which of the following are true, when the cells are connected in series?


405) A milli voltmeter of 25 milli volt range is to be converted into an ammeter to 25 ampere range. The value (in ohm) of necessary shunt will be


406) Two identical heaters of 220V , 1000 W are placed in parallel with each other across 220V line, then the combined power is


407) The resistance of a straight conductor does not depend on its


408) The rate of increase of thermo e.m.f. with temperature at the neutral temperature of a thermocouple


409) When 1 A current flows for 1 min through a silver voltmeter, it deposits 0.067 g of silver on the cathode, then how much charge will flow to deposit 108 g of silver?


410) Consider the following two statements A and B, and identify the correct choice out of given answers
A. Thermo e.m.f. is minimum at neutral temperature of a thermocouple
B. When two junctions made of two different metallic wires are maintained at different temperatures, an electric current is generated in the circuit.


411) The resistance of an incandescent lamp is


412) A wire of resistance 5.5 ohm is drawn out uniformly so that its length is increased twice. Then its new resistance is


413) A battery of e.m.f. 3 volt and internal resistance 1.0 ohm is connected in series with copper voltmeter. The current flowing in the circuit is 1.5 amperes. The resistance of voltmeter will be


414) Potentiometer measures the potential difference more accurately than a voltmeter because


415) The thermocouple among the following that can produce maximum thermo-emf for the same temperature difference between the junction is


416) In a meter bridge, the balancing length from the left end (standard resistance of one ohm is in the right gap) is found to be 20 cm. The value of the unknown resistance is


417) Water boils in an electric kettle in 15 minutes after switching on. If the length of the heating wire is decreased to 2/3 of its initial value, then the same amount of water will boil with the same supply voltage in


418) Charge Q is divided into two parts which are then kept some distance apart. The force between them will be maximum if the two parts are having the charge


419) A steady current is set up in a metallic wire of non-uniform cross-section. How is the rate of flow of electrons (R) related to the area of cross-section (A)?


420) If a current is allowed to pass through a circuit consisting of two dissimilar metals, there is either evolution or absorption of heat at the junction, depending upon the direction of the current. The effect is known as


421) Two electric bulbs A and B are rated as 60 W and 100 W. They are connected in parallel to the same source. Then


422) The atomic weight of silver and copper are 108 and 64. A silver voltmeter and a copper voltmeter are connected in series and when current is passed 10.8 gm of silver is deposited. The mass of copper deposited will be


423) In order to increase the sensitivity of galvanometer


424) 1) The product of a volt and a coulomb is a joule
(2) The product of a volt and an ampere is a joule/second
(3) The product of volt and watt is horse power
(4) Watt-hour can be measured in terms of electron volt
State if


425) Two bulbs consume same power when operated at 200 V and 300 V respectively. When these bulbs are connected in series across a DC source of 400 V then the ratio of power consumed across them is


426) 100 cells each of e.m.f. 5 V and internal resistance 1 ohm are to be arranged so as to produce maximum current in a 25 ohm resistance. Each row is to contain equal number of cells. The number of rows should be


427) If 96500 coulombs of electricity liberates one gram equivalent of any substance, the time taken for a current of 0.15 amperes to deposit 20mg of copper from a solution of copper sulphate is (Chemical equivalent of copper = 32)


428) Two bulbs when connected in parallel to a source take 100 W each. The total power consumed when they are connected in series with the same source is


429) A current of 2.0 ampere passes through a cell of e.m.f. 1.5 volt having internal resistance of 0.15 ohm. The potential difference measured, in volt, across both the ends of the cell will be


430) The resistance of a heater coil is 110 ohm. A resistance R is connected in parallel with it and the combination is joined in series with a resistance of 11 ohm to a 220 volt main line. The heater operates with a power of 110 watt. The value of R in ohm is


431) A piece of fuse wire melts when a current of 15 ampere flows through it. With this current, if it dissipates 22.5 W, the resistance of fuse wire will be


432) Two identical electric lamps marked 500 W, 220 V are connected in series and then joined to a 110 V line. The power consumed by each lamp is


433) The potentiometer is superior to a voltmeter for measuring a potential difference because


434) Two wires A and B of same material and mass have their lengths in the ratio 1:2. On connecting them to the same source, the rate of heat dissipation in B is found to be 5W. The rate of heat dissipation in A is


435) The heat produced by a 100 W heater in 2 min will be equal to


436) In a conductor 4 coulomb of charge flows for 2 seconds. The value of electric current will be


437) Silver and copper voltameters are connected in parallel with a battery of emf 12 V. In 30 min 1 g of silver and 1.8 g of copper are liberated. The energy supplied by the battery is


438) The resistivity of a wire


439) The potential difference in open circuit for a cell is 2.2 volt. When a 4 ohm resistor is connected between its two electrodes the potential difference becomes 2 volt. The internal resistance of the cell will be


440) If the electric current through an electric bulb is 3.2 A, the number of electrons flow through it in one second is


441) Find the true statements


442) A battery of emf E has an internal resistance r. A variable resistance R is connected to the terminals of the battery. A current i is drawn from the battery. V is the terminal potential difference. If R alone is gradually reduced to zero, which of the following best describes i and V?


443) A battery is charged at a potential of 15 V for 8 hours when the current flowing is 10 A. The battery on discharge supplies a current of 5 A for 15 hours. The mean terminal voltage during discharge is 14 V. The "Watt-hour" efficiency of the battery is


444) For electroplating a spoon, it is placed in the voltmeter at


445) A wire of resistance R is divided in 10 equal parts. These parts are connected in parallel, the equivalent resistance of such connection will be


446) Two electroplating cells, one of silver and another of aluminium are connected in series. The ratio of the number of silver atoms to that of aluminium atoms deposited during time t will be


447) An electric kettle boils some water in 16 min. Due to some defect, it becomes necessary to remove 10% turns of heating coil of the kettle. Now, how much time will it take to boil the same of water?


448) A cold-water pipe and a hot-water pipe are both made of copper and are initially electrically isolated. In which one of the following arrangements will the galvanometer indicate a thermo-electric current?


449) The resistance of a galvanometer is 90 ohm. If only 10 percent of the main current may flow through the galvanometer, in which way and of what value, a resistor is to be used


450) A 5.0 A current is setup in an external circuit by a 6.0 storage battery for 6.0 min. The chemical energy of the battery is reduced by


451) An electric bulb is marked 100 W, 230 V. If the supply voltage drops to 115 V, what is the total energy produced by the bulb in 10 min?


452) Three bulbs of 40 W, 60 W, 100 W are arranged in series with 220 volt supply. Which bulb has minimum resistance


453) The conductivity of a superconductor is


454) A colour coded carbon resistor has the colours orange, blue, green and silver. Its resistance value and tolerance percentage respectively are


455) For driving a current of 2 A for 6 minutes in a circuit, 1000 J of work is to be done. The e.m.f. of the source in the circuit is


456) A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10 divisions per milliampere and voltage sensitivity is 2 divisions per millivolt. In order that each division reads 1V, the resistance in Ohm’s needed to be connected in series with the coil will be


457) Kirchhoff’s second law is based on the law of conservation of


458) A battery of e.m.f. 10 V and internal resistance 0.5 ohm is connected across a variable resistance R. The value of R for which the power delivered in it is maximum is given by


459) Which factor is immaterial for the wire used in electric fuse?


460) An ammeter of 5 ohm resistance can read 5 mA. If it is to be used to read 100 volt, how much resistance is to be connected in series


461) The potential difference across the terminals of a battery is 50 V when 11 A current is drawn and 60 V when 1 A current is drawn. The e.m.f. and the internal resistance of the battery are


462) Two electric bulbs have ratings respectively of 25 W, 220 V and 100 W, 220 V. If the bulbs are connected in series with a supply of 440, which bulb will fuse?


463) Express which of the following setups can be used to verify Ohm’s law


464) The thermo emf produced in a thermo-couple is 3 microvolt per degree centigrade. If the temperature of the cold junction is 20℃ and the thermo emf is 0.3 millivolt, the temperature of the hot junction is


465) Metals have


466) When a charged particle of charge e revolves in circular orbit of radius r with frequency n, then orbital current will be


467) If a 2 kW boiler is used everyday for 1 hour, then electrical energy consumed by boiler in thirty days is


468) A steady current i is flowing through a conductor of uniform cross-section. Any segment of the conductor has


469) A coil takes 15 min to boil a certain amount of water; another coil takes 20 min for the same process. Time taken to boil the same amount of water when both coils are connected in series


470) To liberate two litres of hydrogen at 222.4 atmosphere from acidulated water the quantity of electricity that must pass through is


471) A galvanometer having a resistance of 8 ohm is shunted by a wire of resistance 2 ohm. If the total current is 1 amp, the part of it passing through the shunt will be


472) If two electric bulbs have 40 W and 60 W rating at 220 V, then the ratio of their resistances will be


473) Forty electric bulbs are connected in series across a 220 V supply. After one bulb is fused, the remaining 39 are connected again in series across the same supply. The illumination will be


474) A heater draws a current of 2A when connected to a 250 V source. The rate of energy dissipation is


475) A heater coil is cut into two parts of equal length and one of them is used in the heater. The ratio of the heat produced by this half coil to that by the original coil is


476) If two wires having resistances R and 2R both are joined in series and in parallel, then ratio of heat generated in this situation, applying the same voltage is


477) What determines the emf between the two metals placed in an electrolyte?


478) A small power station supplies electricity to 5000 lamps connected in parallel. Each lamp has a resistance of 220 and is operated at 220 V. The total current supplied by the station is


479) An emf of 0.9 V is generated when the temperature difference hot and cold junction of thermocouple is 75 K. Assuming that the thermo emf is directly proportional to the temperature difference, the extent to which the thermo emf will change when the cold junction is heated up by 15 K is


480) If the balance point is obtained at the 35 th cm in a meter bridge, the resistances in the left and right gaps are in the ratio of


481) A lead acid accumulatory (storage battery) is connected to a battery charge for over night charging. Which of the following observations will indicate that the battery was partly charged during the next morning


482) In a thermocouple, the temperature that does not depend on the temperature of the cold junction is called


483) A current I is passed for a time t through a number of voltmeters. If m is the mass of a substance deposited on an electrode and z is its electrochemical equivalent, then


484) A thermocouple is made from two metals, Antimony and Bismuth. If one junction of the couple is kept hot and the other is kept cold, then, an electric current will


485) Electroplating does not help in


486) In a circuit 5 percent of total current passes through a galvanometer. If resistance of the galvanometer is G then value of the shunt is


487) When a current I flows through a wire, the drift velocity of the electrons is v. When current 2I flows through another wire of the same material having double the length and double the area of cross-section, the drift velocity of the electrons will be


488) A cell of e.m.f. E connected with an external resistance R, then p.d. across cell is V. The internal resistance of cell will be


489) An external resistance R is connected to a battery of e.m.f. V and internal resistance r. The joule heat produced in resistor R is maximum when R is equal to


490) A Daniel cell is balanced on 125cm length of a potentiometer wire. Now the cell is short-circuited by a resistance 2 ohm and the balance is obtained at 100 cm. The internal resistance of the Daniel cell is


491) A moving coil galvanometer is converted into an ammeter reading upto 0.03 A by connecting a shunt of resistance 4r across it and into an ammeter reading upto 0.06 A when a shunt of resistance r is connected across it. What is the maximum current which can be sent through this galvanometer if no shunt is used


492) A 25 watt, 220 volt bulb and a 100 watt, 220 volt bulb are connected in series across a 220 volt lines. Which electric bulb will glow more brightly


493) The electric resistance of a certain wire of iron is R. If its length and radius are both doubled, then


494) A coil develops heat of 800 cal/sec. When 20 volts is applied across its ends. The resistance of the coil is (1 cal = 4.2 joule)


495) When the temperature difference between hot and cold junctions of a thermo-couple is 100 K an emf of 1 V is generated. Assume the cold junction is heated by 20 K, the percentage change in thermo emf is


496) The amount of charge required to liberate 9 gm of aluminium (atomic weight =27 and valency = 3) in the process of electrolysis is (Faraday’s number =96500 coulombs/gm equivalent)


497) In a potentiometer, the null points are received at 7th wire. If now we have to change the null points at 9th wire, what should we do?


498) In a copper voltmeter experiment, current is decreased to one-fourth of the initial value but is passed for four times the earlier duration. Amount of copper deposited will be


499) A 500 W heating unit is designed to operate from a 115 volt line. If the line voltage drops to 110 volt, the percentage drop in heat output will be


500) The temperature at which thermal electric power of a thermo couple becomes zero is called


501) A thermister is dipped in a bath whose temperature is to be measured. When the temperature increase the current also increase, because of decreases in


502) When the current i is flowing a conductor, the drift velocity is v. If 2i current is flowed through the same metal but having double the area of cross-section, then the drift velocity will be


503) The material of wire of potentiometer is


504) If two identical heaters each rated as (1000 W-220 V) are connected in parallel to 220 V, then the total power consumed is


505) It is possible that any some constant value of emf, but the potential difference between the plates is zero?


506) A current of two ampere is flowing through a cell of e.m.f. 5 volt and internal resistance 0.5 ohm from negative to positive electrode. If the potential of negative electrode is 10 V, the potential of positive electrode will be


507) The resistance of the filament of a lamp increases with the increase in temperature. A lamp rated 100 W and 200 V is connected across 220 V power supply. If the voltage drops by 10%, then the power of the lamp will be


508) An ammeter gives full scale deflection when current 1.0 A is passed in it. To convert it into 10 A range ammeter, the ratio of its resistance and the shunt resistance will be


509) A storage battery has e.m.f. 15 volt and internal resistance 0.05 ohm. Its terminal voltage when it is delivering 10 ampere is


510) If 10 A deposits 10.8 g of silver in 25 min, how much copper would deposit when 9 A current flows for 20 min.?


511) A constant voltage is applied between the two ends of a uniform metallic wire. Some heat is developed in it. The heat developed is doubled if


512) A silver and a zinc voltmeter are connected in series and a current I is passed through them for a time t, liberating w gram of zinc. The weight of silver deposited is nearly


513) When current is passed in antimony-bismuth couple, then


514) 12 cells each having same emf are connected in series with some cells wrongly connected. The arrangement is connected in series with an ammeter and two cells which are in series. Current is 3 A when cells and battery aid each other and is 2 A when cells and battery oppose each other. The number of cells wrongly connected is


515) Equal amounts of a metal are converted into cylindrical wire of different lengths L and cross-sectional area A. The wire with the maximum resistance is the one, which has


516) What will happen when a 40 watt, 220 volt lamp and 100 watt, 220 volt lamp are connected in series across 40votl supply


517) The two ends of a uniform conductor are joined to a cell of e.m.f. E and some internal resistance. Starting from the midpoint P of the conductor, we move in the direction of current and return to P. The potential V at every point on the path is plotted against the distance covered (x). Which of the following graphs best represents the resulting curve?


518) How many calories of heat will be produced approximately in a 210 W electric bulb in 5 min?


519) Resistors of 1, 2, 3 ohm are connected in the form of a triangle. If a 1.5 volt cell of negligible internal resistance is connected across 3 ohm resistor, the current flowing through this resistance will be


520) An electric kettle has two heating coils. When one coil is used, water in the kettle boils in 5 minutes, while when second coil is used, same water boils in 10 minutes. If the two coils, connected in parallel are used simultaneously, the same water will boil in time


521) A 25 W and 100 W bulbs are joined in series and connected to the mains. Which bulb will glow brighter?


522) A battery has e.m.f. 4 V and internal resistance r. When this battery is connected to an external resistance of 2 ohm, a current of 1 amp.flows in the circuit. How much current will flow if the terminals of the battery are connected directly


523) The thermistors are usually made of


524) The thermistors are usually made of, if length is doubled, the drift velocity


525) The value of internal resistance of an ideal cell is


526) Two bulbs 25 W, 220 V and 100 W, 220 V are given. Which has higher resistance?


527) We have two wires A and B of same mass and same material. The diameter of the wire A is half of that B. If the resistance of wire A is 24 ohm then the resistance of wire B will be


528) A heater of 220 V heats a volume of water in 5 min time. A heater of 110 V heats the same volume of water is


529) Which of the following is not reversible?


530) The following four wires are made of the same material and are at the same temperature. Which one of them has highest electrical resistance?


531) As the temperature rises the resistance offered by metal


532) Pick out the wrong statement


533) When the length and area of cross-section both are doubled, then its resistance


534) The masses of three wires of copper are in the ratio 1:3:5 and lengths are in the ratio 5:3:1. Then the ratio of their electrical resistances are


535) Electric power is transmitted over long distances through conducting wires at high voltage because


536) Two bulbs of 250 V and 100 W are first connected in series and then in parallel with a supply of 250 V. Total power in each of the case will be respectively


537) A 50 ohm galvanometer gets full scale deflection when a current of 0.01 A passes through the coil. When it is converted to a 10 A ammeter, the shunt resistance is


538) In a wire of circular cross-section with radius r, free electrons travel with a drift velocity V when a current I flows through the wire. What is the current in another wire of half the radius and of the same material when the drift velocity is 2V


539) One end each of a resistance r capacitor C and resistance 2r are connected together. The other ends are respectively connected to the positive terminals of batteries, P, Q, R having respectively emf’s E, E and 2E. the negative terminals of the batteries are then connected together. In this circuit, with steady current the potential drop across the capacitor is


540) The speed at which the current travels, in a conductor, is nearly


541) If the length of filament of a heater is reduced by 10%, the power of the heater will


542) The electric current passing through a metallic wire produces heat because of


543) According to Joule’s law, if the potential difference across a conductor having a material of specific resistance remains constant, then the heat produced in the conductor is directly proportional to


544) n conducting wires of same dimensions but having resistivites 1, 2, 3,…..n are connected in series. The equivalent resistivity of the combinations is


545) If a wire of resistance 20Ω is covered with ice and a voltage of 210 V is applied across the wire, then the rate of melting of ice is0.85g/s


546) The length of a given cylindrical wire is increased by 100%. Due to the consequent decrease in diameter the change in the resistance of the wire will be


547) The plates of a charged condenser is connected to a voltmeter. If the plates are moved apart, the reading of voltmeter will


548) If the length of filament of a heater is reduced by 10%, the power of the heater will