Practice Test

Q1) Which one of the following is not the advantage of semi conductor device over tubes ? Show Answer

Q2) P-N junction can be used as : Show Answer

Q3) To provide the abundance of holes the impurity added should be : Show Answer

Q4) For forward biasing P-N junction the positive terminal of the battery is connected to : Show Answer

Q5) The number of functions in a transistor is : Show Answer

Q6) The number of terminals in a transistor is : Show Answer

Q7) To produce N-type crystal Ge or Si may be doped with a substance that is : Show Answer

Q8) Transistor was invented by : Show Answer

Q9) In n-p-n transistor, P-type crystal is : Show Answer

Q10) The base of a transistor serves a similar function as : Show Answer

Q11) A p-type semiconductor can be obtained by adding : Show Answer

Q12) The current gain for common base configuration is 0.95. What is the current gain in common emitter configuration ? Show Answer

Q13) Frequency of an oscillator is given by : Show Answer

Q14) In the binary system the number 100 represents : Show Answer

Q15) In NOT operation if Y is output and A is input, then : Show Answer

Q16) A triode valve has an amplification factor 20 and its plate potential is 300 V. What should be the grid potential to reduce the plate current zero ? Show Answer

Q17) Diode value can be used as : Show Answer

Q18) The pure semiconductor has : Show Answer

Q19) The type of bonding in Ge crystal is : Show Answer

Q20) N-type Ge is obtained on doping the Ge crystal with : Show Answer

Q21) A P-type crystal is obtained by doping :
(A) silicon with arsenic
(B) silicon with aluminium
(C) Ge with boron
(D) Ge with phosphorus. Show Answer

Q22) Majority current carries in N-Types are : Show Answer

Q23) The number of valency electrons in a good conductor is generally : Show Answer

Q24) The electrons are forbidden in a brand in a crystal called the : Show Answer

Q25) The behaviour of Ge as a semiconductor is due to the width of : Show Answer

Q26) When triode is used as an amplifier, the phase difference between the input signal voltage and the output is : Show Answer

Q27) Three triodes having amplification factors of 12,18,36 and with mutual conductance 3,6, 4m A/V respectively are operated in parallel. What is the equivalent mutual conductance ? Show Answer

Q28) The current gain of common-base circuit is 0.97, what is the current gain of common-emitter circuit ? Show Answer

Q29) When we apply reverse bias to a junction diode it : Show Answer

Q30) The depletion layer in the P-N junction is caused by : Show Answer

Q31) Digital circuits can be made to be respective use of Show Answer

Q32) NOR gate is a combination of Show Answer

Q33) The output of a 2 input OR gate is 0 only what its : Show Answer

Q34) A solid having uppermost energy - band partially filled with electrons is called : Show Answer

Q35) A transistor is preferable to a triode valve when used as amplifier because it : Show Answer

Q36) What is the atomic radius of a BCC crystal structure? Show Answer

Q37) In a cubic unit cell of bcc structure, the lattice points or the number of atoms are : Show Answer

Q38) The number of modules per unit cell in fcc lattice is : Show Answer

Q39) The crystal has fcc structure and its lattice constant is 3.5 A. Its atomic radius is : Show Answer

Q40) The ratio of atomic radius 'r' and lattice parameter 'a' of fcc system is : Show Answer

Q41) The co - ordination number of hexagonal close packing [hcp] is : Show Answer

Q42) Polymers are : Show Answer

Q43) Of the various cubic systems, one having closed packing is : Show Answer

Q44) In which of the following states of matter the atomic kinetic and potential energies are comparable ? Show Answer

Q45) CuNi exhibits : Show Answer

Q46) Which of the binding is weakest in strength ? Show Answer

Q47) Which of the following is supercooled ? Show Answer

Q48) The ionic crystals are : Show Answer

Q49) MgO exhibits : Show Answer

Q50) Metallic solids are always opaque because : Show Answer

Q51) What helped in the study of the geometry of the internal structured of the crystals ? Show Answer

Q52) Quartz is a crystalline solid because it is : Show Answer

Q53) Silver has fcc structure. If the interatomic spacing is 2.888 A, the lattice constant is : Show Answer

Q54) The density of a crystalline material is equal to the : Show Answer

Q55) Which of the following properties are common to liquids and amorphous solids ? Show Answer

Q56) What is co-ordination number ? The no. of the : Show Answer

Q57) In a semiconductor diode, the reserve biased current is due to drift of free electrons and holes caused by : Show Answer

Q58) Which one of the following shows correctly the input characteristics of a transistor in common base configuration ? Show Answer

Q59) In a semiconductor crystal, if the current flows due to breakage of crystal bonds, then the semiconductor is called : Show Answer

Q60) When two semiconductors of P and N-type are brought into contact, they form a P-N junction which acts like a : Show Answer

Q61) In the case of forward biasing of P-N junction, which one of the following figures correctly depicts the direction of flow of charge carriers ? Show Answer

Q62) In an n-P-N-P transistor circuit, the collector current is 10 mA. If 90% of the electrons emitted reach the collector : Show Answer

Q63) On increasing the reverse bias to a large value in a P-N junction diode current : Show Answer

Q64) When N- type of semiconductor is heated Show Answer

Q65) The depletion layer in the P-N junction region is caused by : Show Answer

Q66) How many NAND gates are used to form AND gate ? Show Answer

Q67) what are ripples ? Show Answer

Q68) The "FREE ELECTRON " model of metallic solid does not explain : Show Answer

Q69) Who was first to use Boolean algebra for describing the operation of logic gates ? Show Answer

Q70) Which gate is formed by inverting the output of AND gate ? Show Answer

Q71) Ice is an example of : Show Answer

Q72) In a semiconductor, it is found that three quarter of current is being carried by electrons and the quarter by holes. If at this temperature the drift velocity of electrons is two and half times of holes, the the ratio of electrons to holes present is : Show Answer

Q73) Energy bonds in solids are a consequence of : Show Answer

Q74) When aluminium is added as an impurity to silicon, then resulting material is : Show Answer

Q75) In junction diode, the holes are because of : Show Answer

Q76) In the CB mode of a transistor, when the collector voltage is changed by 0.5 volt, the collector current changes by 0.05mA. The output resistance will be : Show Answer

Q77) Which of the following is NOT equal to O in the Boolean algebra ? Show Answer

Q78) In the Boolean algebra which of the following is NOT equal to A ? Show Answer

Q79) The nature of binding for a crystal with alternate and evenly spaced positive and negative ions is : Show Answer

Q80) The energy gap between conduction band and valence band is order of 0.7 eV. It is a : Show Answer

Q81) In bcc crystal, the distance between any two nearest atom is Show Answer

Q82) What account for flow of charge carriers in forward and reserve biasing of silicon p-n diode ? Show Answer

Q83) The intrinsic semiconductor behaves as an insulator at : Show Answer

Q84) For a logic 0101 the waveform is : Show Answer

Q85) Which of the following figure represents an ideal diode characteristics ? Show Answer

Q86) The forward biased diode is : Show Answer

Q87) Which of the following when added as an impurity into the silicon, produces n- type semi - conductor : Show Answer

Q88) In a P-N junction : Show Answer

Q89) In Germanium crystal, impurity donor element have valency : Show Answer

Q90) At 0 K temp., a p-type semiconductor : Show Answer

Q91) The potential barrier in the depletion layer is due to : Show Answer

Q92) Barrier potential of a P- N junction diode does not depend on : Show Answer

Q93) Reverse bias applied on a junction diode : Show Answer

Q94) To a germanium sample, traces of gallium and added as an impurity. The resultant sample would behave like : Show Answer

Q95) Assertion : The resistivity of a semiconductor increases with temperature.
Reason : The atom of a semiconductor vibrate with larger amplitude at higher temperature thereby increasing its resistivity.
Show Answer

Q96) Assertion : In a transistor the base is made thin.
Reason : A thin base makes the transistor stable. Show Answer

Q97) Assertion : A transistor amplifier in common emitter configuration has a low input impedance.
Reason : The base to emitter region is forward biased. Show Answer

Q98) A n-p-n transistor conducts when : Show Answer

Q99) If a full wave rectifier circuit is operating 50 Hz mains, the fundamental frequency ripple will be : Show Answer

Q100) Which of the following can be used as a semiconductor ? Show Answer

Q101) The semiconductor at room temperature : Show Answer

Q102) The peak voltage in the output of a half wave diode rectifier fed with a sinusoidal signal without filter is 10V. The d.c. component of output voltage is : Show Answer

Q103) The output of OR gate is 1 : Show Answer

Q104) In a P-N junction photo-diode, the value of the photo electromotive force produced by monochromatic lights is proportional to : Show Answer

Q105) A rectifier converts : Show Answer

Q106) Copper has face centered cubic (fcc) lattice with interatomic spacing equal to 2.54 A. The value of lattice constant for this lattice is : Show Answer

Q107) Which of the following logic gates is an universal gate ? Show Answer

Q108) Consider an n-p-n transistor amplifier in common emitter configuration . The current gain of the transistor is 100. If the collector changes by 1 mA, what will be the change in emitter current ? Show Answer

Q109) Application of a forward bias to a P-N junction : Show Answer

Q110) Zener diode is used for : Show Answer

Q111) When a P-N diode is reverse biased then : Show Answer

Q112) The output of a diode rectifier is : Show Answer

Q113) In intrinsic semiconductor at room temperature, number of electrons and holes are : Show Answer

Q114) Enetordy of a superconductor is : Show Answer

Q115) The amplification factor of a triode depends on the : Show Answer

Q116) A pentode can be used : Show Answer

Q117) A modulator is used for : Show Answer

Q118) Degree of modulation : Show Answer

Q119) The static amplification factor of a triode value depends upon : Show Answer

Q120) The fourth electrode in a tetrode is to : Show Answer

Q121) The input a.c current frequency to a full wave rectifier is v then the output frequency of the current is : Show Answer

Q122) A triode value has an amplification factor of 15. There is a change in the grid voltage by 0.3 volt, then by how much should the plate voltage change as to keep the current constant ? Show Answer

Q123) What is the minimum number of parameters required to describe a three dimension crystal system : Show Answer

Q124) The energy gab between the valence band and the conduction band for a material is 6 eV. The material is, Show Answer

Q125) An a.c. signal of 50 Hz frequency is input of a full wave rectifier using two diodes. The output frequency after full wave rectification is Show Answer

Q126) In a transistor in the common emitter mode : Show Answer

Q127) When the input of a two logic gate are 0 and 0, the output is 1. When the inputs are 1 and 0 the output is zero. The logic gate is of the type : Show Answer

Q128) The impurity atoms with which a pure silicon should be doped to make a p-type semiconductor is : Show Answer

Q129) At room temperature,a p-type semi conductor has : Show Answer

Q130) The least region in a transistor is : Show Answer

Q131) NAND gate is : Show Answer

Q132) In an NPN transistor the collector current is 24 mA. If 80% of electrons reach collector its base current in mA is : Show Answer

Q133) For a cubic crystal structure which one of the following relations indicating the cell characteristics is correct ? Show Answer

Q134) A p-n photodiode is made of a material with a band gap of 2.0 eV. The minimum frequency of the radiation that can be absorbed by the material is nearly : Show Answer

Q135) The voltage gain of an amplifier with 9% negative feedback is 10. The voltage gain without feedback will be : Show Answer

Q136) A p-n photodiode is fabricated from a semiconductor with a band gap of 2.5 eV. It can detect a signal of wavelenght. Show Answer

Q137) Which one of the following statement is FALSE ? Show Answer

Q138) The device that can act as a complete electronic circuit is : Show Answer

Q139) In forward biasing of the p-n junction : Show Answer

Q140) The co-ordination number for a body centred cubic cell is : Show Answer

Q141) The lattice parameter for a crystalline structure is 3.6 A. Atomic radius in simple cubic crystal is : Show Answer

Q142) The atomic radius for a face centred cubic cell of lattice parameter a is : Show Answer

Q143) In a transistor : Show Answer

Q144) Truth table of NOR gate is : Show Answer

Q145) The space lattice of diamond is : Show Answer

Q146) The conductivity of a semiconductor is given by Show Answer

Q147) A hole diffuses from the P-side to the N-side in a P-N junction. This means that : Show Answer

Q148) The number of molecules per unit cell in fcc lattice is : Show Answer

Q149) Which of the following types of binding produces crystals that are transparent to visible light and conduct electricity only at higher temperatures ? Show Answer

Q150) In case of diamond, the forbidden gap is about : Show Answer

Q151) Metallic solids are always opaque because : Show Answer

Q152) If r is the input resistance and R is the output resistance (R > r), the voltage gain in common emitter configuration is : Show Answer

Q153) If r is the input resistance and R is the output resistance (R > r), the voltage gain in common base configuration is : Show Answer

Q154) The ionization track of a subatomic particle can be photographed in : Show Answer

Q155) Rubber is an example of : Show Answer

Q156) Which of the following is not the property of a crystalline substance ? Show Answer

Q157) The minimum proportion of available volume which may be filled by hard spheres arranged in various structures is : Show Answer

Q158) Atoms of copper sulphate crystal are arranged in : Show Answer

Q159) If N is Avogadro's number, M the atomic weight and d is density, the number of free electrons per unit volume of a monovalent metallic crystal can be expressed as : Show Answer

Q160) The atomic packing factor for a fcc cell is : Show Answer

Q161) Zener diode is used for Show Answer

Q162) When an impurity is doped into an intrinsic semiconductor the conductivity of the semiconductor Show Answer

Q163) Silicon is a semiconductor. If a small amount of As is added to it, then its electrical conductivity Show Answer

Q164) The valency of an impurity element added to germanium crystal in order to convert it into P - type semiconductor is Show Answer

Q165) An intrinsic - semiconductor at absolute zero of temperatures behaves as Show Answer

Q166) To a germanium sample, traces of gallium are added as an impurity. The resultant sample would behave like Show Answer

Q167) The typical ionisation energy of a donor in silicon is Show Answer

Q168) If the forward voltage in a diode is increased, the width of the depletion region Show Answer

Q169) The impurity atom that should be added to Germanium to make its n - type is Show Answer

Q170) Statement 1 : An n-type semiconductor has a large number of electrons but still it is electrically neutral.
Statement 2 : An n-type semiconductor is obtained by doping an intrinsic semiconductor with a pentavalent impurity.
Show Answer

Q171) Statement 1 : The conductivity of a semiconductor increases with rise of temperature.
Statement 2 : On rising temperature covalent bonds of semiconductor break.
Show Answer

Q172) In semiconductors at a room temperature Show Answer

Q173) The dominant contribution to current comes from holes in case of Show Answer

Q174) Diffusion current in a p-n junction is grearer than the drift current in magnitude Show Answer

Q175) For germanium crystal, the forbidden energy gap in joule is Show Answer

Q176) The band gap in germanium and silicon in eV respectively is Show Answer

Q177) The cathode of a diode valve is emitting electrons when it is heated. The valve is connected in a circuit. When the circuit is closed, what happens to the emission of electrons ? Show Answer

Q178) In an n-type semiconductor, donor valence band is Show Answer

Q179) If no external voltage is applied across p-n junction, there would be Show Answer

Q180) When the conductivity of a semiconductor is only due to breaking of covalent bonds, the semiconductor is called Show Answer

Q181) Reverse bias applied to a junction diode Show Answer

Q182) The current amplification of the common base N P N transistor is 0.96. What is the current gain if it is used as common emitter amplifier ? Show Answer

Q183) The electron energy states in a solid are shown in terms of bands ( not sharp levels, as for atoms). In a semiconductor we have electrons in conduction band, inner bands, and valence band. Now which of the following is incorrect ? Show Answer

Q184) Statement 1 : The probability of electrons to be found in the conduction band of an intrinsic semiconductor at a finite temperature decrease exponentially with increasing band gap
Statement 2 :It will be more difficult for the electron to cross over the large band gap while going from valence band to conduction band.
Show Answer

Q185) Statement 1 : The temperature coefficient of resistance is positive for metals and negative for p-type semiconductor
Statement 2 : The effective charge carriers in metals are negatively charged whereas in p-type semiconductor, they are positively charged.
Show Answer

Q186) What will be the forward current at a forward voltage of 0.6 V ? Show Answer

Q187) What will be the increase in the current, if the voltage across the diode is increased to 0.7 V ? Show Answer

Q188) What is the dynamic resistance ? Show Answer

Q189) Which of the following is not analogue signal ? Show Answer

Q190) Refer to the circuit shown in figure. What inputs X and Y will produce a high output at R ? Show Answer

Q191) How many NAND gates are required to make an OR gate ? Show Answer

Q192) Statement 1 : NAND or NOR gates are called digital building blocks.
Statement 2 : The repeated use of NAND ( or NOR ) gates can produce all the basic or complicated gates
Show Answer

Q193) Statement 1 : NOT gate is also called invertor circuit.
Statement 2 : NOT gate inverts the input order.
Show Answer

Q194) The circuit above behaves as Show Answer

Q195) If all the NOR gate in the circuits are replaced by NAND gates, the circuit would perform the logic operation of Show Answer

Q196) The output of OR gate is 1 Show Answer

Q197) The boolean expression for NAND gate is Show Answer

Q198) If A = 1 and B = 0, then A.A + B in the boolean expression is equal to Show Answer

Q199) Which of the following is the logic symbol of NAND gate ? Show Answer

Q200) If one terminal of an XOR gate is kept at 1, the output will be zero when the other terminal is at Show Answer

Q201) In boolean algebra, which of the following is not equal to zero Show Answer

Q202) Which of the following is not correct ? Show Answer

Q203) Identify the gate in box II Show Answer

Q204) Identify the gate in box III Show Answer

Q205) An AND gate can be prepared by repetitive use of Show Answer

Q206) The number of NAND gates required to make NOT gate is Show Answer

Q207) Statement 1 : In a two input NAND gate if one of the inputs is kept high, it acts as an inverter.
Statement 2 : A low input produces a high output in NAND gate
Show Answer

Q208) The logic gate circuit is Show Answer

Q209) Which one of the following cirucits would give waveforms as given in the passage above Show Answer

Q210) What is the forbidden energy gap (in joule) for a Germanium crystal? Show Answer

Q211) There is a small energy gap between the conduction and valence bands of Show Answer

Q212) Silicon and copper are cooled from 300 K to 100 K. The specific resistance (resistivity) Show Answer

Q213) The highest energy level which can be occupied by an electron in valence band at OK is known as Show Answer

Q214) At absolute zero Si acts as Show Answer

Q215) The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in the Show Answer

Q216) Choose only the wrong statement from the following: Show Answer

Q217) In good conductors the gap between the valence band and the conduction band is Show Answer

Q218) Carbon, silicon and germanium atoms have four valence electrons each. At room temperature, which of the following statements is most appropriate? Show Answer

Q219) What is the name of the level formed due to the impurity atom in the forbidden energy gap near the valence band in a p-type semiconductor? Show Answer

Q220) The impurity atom with which pure silicon should be doped to make a p type semiconductor is Show Answer

Q221) What is the change in resistance and electrical conductivity of a semiconductor, when its temperature is increased? Show Answer

Q222) In a semiconductor, the energy gap between the valence and conduction bands is 1.1 eV. It is expressed in joules as Show Answer

Q223) The mobility of mobile holes is less than that of mobile electrons because Show Answer

Q224) The electrical conductivity of pure silicon can be increased by Show Answer

Q225) Find the 'wrong' statement from the following:
In a semiconductor
Show Answer

Q226) Which is the wrong statement from the following? Show Answer

Q227) Choose the false statement from the following. Show Answer

Q228) Intrinsic semiconductor is electrically neutral. Extrinsic semiconductor having large number of current carriers is Show Answer

Q229) There are two Ge crystals A and B. Few aluminium atoms are added to A while few Indium atoms are added to B. Then Show Answer

Q230) By increasing the temperature, the specific resistance of a conductor and a semiconductor Show Answer

Q231) In semiconductors at a room temperature Show Answer

Q232) A semiconductor has phosphorus as impurity, then it will have Show Answer

Q233) In a p-type semiconductor, germanium is dopped with Show Answer

Q234) In an insulator Show Answer

Q235) Small pieces of Copper and Germanium are cooled from room temperature to 100 K. Then the resistance of Show Answer

Q236) When the electrical conductivity of a semi-conductor is only due to the breaking of its covalent bonds, then the semiconductor is said to be Show Answer

Q237) In case of a semiconductor, which one of the following statements is wrong? Show Answer

Q238) Which one of the following, when added as an impurity to silicon, produces an n-type semiconductor? Show Answer

Q239) The increase in temperature of a semiconductor, will Show Answer

Q240) Which one of the following statements is wrong?
When a potential difference is applied across, the current passing through Show Answer

Q241) When a battery is connected to a p-type semiconductor with a metallic wire, the current in the semiconductor (predominantly), inside the metallic wire and that inside the battery respectively is due to Show Answer

Q242) A semiconducting device is connected in series with a battery and a resistance. A current of 10 mA is found to pass through the circuit. If the polarity of the battery is reversed, the current drops to almost zero. The device may be Show Answer

Q243) If the forward bias voltage of a junction diodes is increased from 0.8V to 2V, the current increases by 4 mA. The forward resistance of the diode is Show Answer

Q244) A half wave rectifier is used to rectify an alternating voltage of frequency 60 Hz. The number of pulses of rectified current obtained in one second is Show Answer

Q245) In which one of the following devices the reverse biased characteristics of a p-n junction diode are used? Show Answer

Q246) A junction diode is forward biased. If the forward voltage is increased from 0.4 V to 0.7 V, the forward current changes by 1.5 mA. What is the forward resistance of the junction diode? Show Answer

Q247) The depletion region of a p-n junction is formed Show Answer

Q248) In a halfwave rectifier, the output frequency is 50 Hz if the input frequency is 50 Hz. What is the output frequency of a fullwave rectifier for the same input frequency? Show Answer

Q249) When the resistance between p and n regions is very high then the p-n junction diode acts as Show Answer

Q250) In a p - n junction, electric conduction takes place due to Show Answer

Q251) The current obtained from a filterless rectifier is Show Answer

Q252) In the case of a p-n junction diode, if the reverse bias is very high, there is a sudden large increase in current. In this case the value of reverse bias voltage is known as Show Answer

Q253) What happens to the depletion region of a p-n junction? Show Answer

Q254) When the p-end of the p-n junction is connected to the negative terminal of the battery and the n-end to the positive terminal of the battery, then the p-n junction behaves like Show Answer

Q255) The electrical circuit used to get smooth d.c. output from a half wave rectifier circuit is called Show Answer

Q256) The depletion layer in the p-n junction region is caused by Show Answer

Q257) In an unbiased p - n junction Show Answer

Q258) The barrier potential of a p-n junction diode does not depend upon the Show Answer

Q259) When a p-n junction diode is forward biased, then Show Answer

Q260) If a full wave rectifier circuit is operating from 50 Hz mains, the fundamental frequency in the ripple will be Show Answer

Q261) The barrier potential of a p-n junction depends on the
(i) type of semi conductor material
(ii) amount of doping
(iii) temperature
Which one of the following is correct? Show Answer

Q262) A rectifier is used to Show Answer

Q263) The frequency of a given AC signal is 50 Hz. When it is connected to a half-wave rectifier, the number of output pulses given by the rectifier in 1 s is Show Answer

Q264) A semiconducting device is connected is series with a battery, a resistance and a microammeter. It is found that there is practically no current in the circuit. But if the polarity of the battery is reversed, there is a sudden increase in the current. The device may be Show Answer

Q265) The dominant mechanism for motion of charge carriers in forward and reverse biased silicon p-n junction are Show Answer

Q266) In the middle of the depletion layer of a reverse biased p-n junction, the Show Answer

Q267) In a p-n junction diode not connected to any circuit Show Answer

Q268) The peak voltage in the output of a half-wave diode rectifier fed with a sinusoidal signal without filter is 10 V. What is the d.c. component of the output voltage? Show Answer

Q269) A semiconductor diode (D) and a resistor R are connected in some way and are kept in a closed box, having two external terminals. When a potential difference of 1 V is applied to their combination, the current I = 25 mA. If the potential difference is reversed, the current becomes 50 mA. What are the values of R and the forward resistance of the diode? Show Answer

Q270) What is the value of D.C. voltage in a half wave rectifier in converting A.C. voltage V = 100 sin (314 t) into D.C.? Show Answer

Q271) Which one of the following is the correct statement regarding the depletion region of an unbiased p-n junction? Show Answer

Q272) The colour of light emitted by a LED depends upon Show Answer

Q273) A general purpose diode is more likely to suffer avalanche breakdown rather than zener breakdown because Show Answer

Q274) GaAs is used to prepare Show Answer

Q275) A solar cell works on the principle of Show Answer

Q276) LEDS used for giving infrared radiations are prepared from Show Answer

Q277) Consider the following statements A and B and identify the correct answer.
(A) A zener diode should be connected in reverse bias for proper functioning.
(B) The potential barrier of a p-n junction lies between 2 V and 5 V. Show Answer

Q278) In a circuit a diode was used and the output voltage across the diode was always 50 volts, even if the input voltage fluctuated between 110 V to 90 V. The diode used in the circuit was Show Answer

Q279) Light emitting diodes are used in 'alphanumeric' displays of advertisements. This means that the display consists of Show Answer

Q280) In a p-i-n diode solar cell, the width of the depletion region is increased by using Show Answer

Q281) Which one of the following currents remains approximately constant, when the source voltage of a zener diode stabiliser is increased? Show Answer

Q282) For emission of light, a light emitting diode (LED) is Show Answer

Q283) When an n-p-n transistor is used as an amplifier Show Answer

Q284) For a transistor circuit in common emitter configuration, the voltage gain is 100. If the input voltage is 20 mV, then the output voltage is Show Answer

Q285) In an npn transistor circuit, the emitter current is 10 mA. If 90% of the emitted electrons reach the collector then the base current is Show Answer

Q286) In a silicon transistor, a change of 7.89 mA in the emitter current, produces a change of 7.8 mA in the collector current, then the base current must change by Show Answer

Q287) A transistor connected in CE mode, has a current gain of 50. If the load resistance is 5 K, input resistance is 1 K and the input peak voltage is 0.4 V, then the peak output voltage will be Show Answer

Q288) In an n-p-n transistor amplifier, the collector current is 9 mA. If 90% of the electrons from the emitter reach the collector, then Show Answer

Q289) What is the current gain for a transistor used as a common emitter amplifier, if the current gain of the same transistor used in common base mode is 0.95? Show Answer

Q290) The difference in the working of a step up transformer and an amplifier is Show Answer

Q291) To obtain the current gain (beta) of a transistor, when it is in CE mode, we use Show Answer

Q292) In a common base amplifier, the phase difference between the input signal voltage and output voltage is Show Answer

Q293) In a transistor amplifier, the collector current is 5.5 mA for an emitter current of 5.6 mA. What is the current amplification factor of the transistor? Show Answer

Q294) If three amplifiers each with a gain of 5 are connected in series, then the overall amplification will be Show Answer

Q295) The current gain of a transistor in common base mode is 0.99. What is the change in collector current if the emitter current changes by 5 mA? Show Answer

Q296) In an n-p-n transistor, the collector current is 24 mA. If 80% of the electrons emitted by the emitter reach the collector, the base current in mA is Show Answer

Q297) In a transistor in CE configuration, the ratio of power gain mrs to voltage gain is Show Answer

Q298) In an n-p-n transistor, if the doping in the base region is increased, then the collector current Show Answer

Q299) In a PNP transistor, N-type semiconductor is used as the Show Answer

Q300) The current gain for a transistor working as common-base amplifier is 0.96, If the emitter current is 7.2 mA, then the base current is Show Answer

Q301) The part of a transistor which is most heavily doped to produce large number of majority carriers is the Show Answer

Q302) An n-p-n transistor conducts when Show Answer

Q303) How many electrodes are there in a transistor? Show Answer

Q304) In a PNP transistor, N-type semiconductor is used as the Show Answer

Q305) Which one of the following is correct, about doping in a transistor? Show Answer

Q306) The current gain of an n-p-n transistor in common emitter configuration is 100. What will be the change in the emitter current, if the collector current changes by 1 mA? Show Answer

Q307) A transistor is used in a common emitter mode as an amplifier. Then Show Answer

Q308) In a common base circuit of a transistor, current amplification factor is 0.95. What is the emitter current if the base current is 0.2 mA? Show Answer

Q309) A NOR gate is ON only when all its inputs are Show Answer

Q310) If two inputs of a NAND gate are shorted, the resulting gate is Show Answer

Q311) For which logic gate the following statement is true?
The output is low if and only if all the inputs are high. Show Answer

Q312) The truth table of a logic gate is a table Show Answer

Q313) For a two input logic gate, the truth table has 4 possible input combinations. For a 3 input logic gate the numbers of combinations (entries) in the input side of the truth table are Show Answer

Q314) The logic expression y = ABC is read as Show Answer

Q315) A NOR gate gives Show Answer

Q316) For which logic gate the following statement is true?
The output is low, if and only if all inputs are low. Show Answer

Q317) How many NAND gates are required to form an AND gate? Show Answer

Q318) In a chemical process, alarm systems are to be activated whenever either the pressure or the temperature in the reaction chamber exceeds certain limits. This is done by using a logic gate whose inputs will be the voltages corresponding to the high temperature or high pressure in the reaction chamber. Which logic gate should be used to activate the alarms? Show Answer

Q319) In a two input logic gate, when one input is 1 and the other is zero, the output is one. But even if both inputs are zero, the output is one, the logic gate is Show Answer

Q320) Which logic gate produces 'LOW' output when any of the inputs is "HIGH"? Show Answer

Q321) If the output of two NAND gates is given to input of a NAND gate. Then the truth table will be of Show Answer

Q322) When a hole is produced in a p-type semiconductor, there is Show Answer

Q323) The colour of light emitted by an LED depends upon Show Answer

Q324) In a semiconductor, acceptor impurity is Show Answer

Q325) The width of the depletion region of a p-n junction diode is Show Answer

Q326) The schematic symbol of light emitting diode is (LED). Show Answer

Q327) Photodiode is a device Show Answer