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) The binary number corresponding to the decimal number 49 is : Show Answer

Q16) OR gate operation means : Show Answer

Q17) In AND operation if Y is output and A and B are inputs the truth table is : Show Answer

Q18) In NOT operation if Y is output and A is input, then : Show Answer

Q19) Under space charge limited conditions the plate current in a diode is 10mA at plate potential of 100 V. If the plate potential is changed to 400V, what is the plate current ? Show Answer

Q20) 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

Q21) Diode value can be used as : Show Answer

Q22) In a p-n-p transistor operating as amplifier with common emitter configurations a change in base current from 100mA to 200mA produces a change in collector current from 10mA to 18mA. Calculate the current grain of transistor : Show Answer

Q23) The pure semiconductor has : Show Answer

Q24) The type of bonding in Ge crystal is : Show Answer

Q25) The conductivity of P-type semiconductor is due to : Show Answer

Q26) N-type Ge is obtained on doping the Ge crystal with : Show Answer

Q27) 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

Q28) Majority current carries in N-Types are : Show Answer

Q29) The number of valency electrons in a good conductor is generally : Show Answer

Q30) The electrons are forbidden in a brand in a crystal called the : Show Answer

Q31) The behaviour of Ge as a semiconductor is due to the width of : Show Answer

Q32) When triode is used as an amplifier, the phase difference between the input signal voltage and the output is : Show Answer

Q33) 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

Q34) The current gain of common-base circuit is 0.97, what is the current gain of common-emitter circuit ? Show Answer

Q35) In a common - base circuit of transistor, current amplification factor is 0.95. Calculate the emitter current , if base current is 0.2 mA. Show Answer

Q36) In case of a p-n junction diode at high value of reserve bias the current raises sharply. The value of reserve bias is know as : Show Answer

Q37) For a transistor the current amplification factor is 0.8. If the transistor is now in common - emitter configuration, the change in collector current when the base current change by 6mA is : Show Answer

Q38) An oscillator in nothing but an amplifier with : Show Answer

Q39) To use a transistor as an amplifier : Show Answer

Q40) When we apply reverse bias to a junction diode it : Show Answer

Q41) The depletion layer in the P-N junction is caused by : Show Answer

Q42) When a P-N junction is resersed biased, the flow of current across the junction is mainly due to : Show Answer

Q43) Digital circuits can be made to be respective use of Show Answer

Q44) NOR gate is a combination of Show Answer

Q45) The output of a 2 input OR gate is 0 only what its : Show Answer

Q46) Crystals exhibit : Show Answer

Q47) A solid having uppermost energy - band partially filled with electrons is called : Show Answer

Q48) A transistor is preferable to a triode valve when used as amplifier because it : Show Answer

Q49) What is the atomic radius of a BCC crystal structure? Show Answer

Q50) The atomic packing factor for a face centered cubic cell is : Show Answer

Q51) In a cubic unit cell of bcc structure, the lattice points or the number of atoms are : Show Answer

Q52) The number of modules per unit cell in fcc lattice is : Show Answer

Q53) The crystal has fcc structure and its lattice constant is 3.5 A. Its atomic radius is : Show Answer

Q54) The ratio of atomic radius 'r' and lattice parameter 'a' of fcc system is : Show Answer

Q55) The co - ordination number of hexagonal close packing [hcp] is : Show Answer

Q56) Polymers are : Show Answer

Q57) Of the various cubic systems, one having closed packing is : Show Answer

Q58) In which of the following states of matter the atomic kinetic and potential energies are comparable ? Show Answer

Q59) CuNi exhibits : Show Answer

Q60) Which of the binding is weakest in strength ? Show Answer

Q61) Which of the following is supercooled ? Show Answer

Q62) The ionic crystals are : Show Answer

Q63) MgO exhibits : Show Answer

Q64) Metallic solids are always opaque because : Show Answer

Q65) What helped in the study of the geometry of the internal structured of the crystals ? Show Answer

Q66) Quartz is a crystalline solid because it is : Show Answer

Q67) Silver has fcc structure. If the interatomic spacing is 2.888 A, the lattice constant is : Show Answer

Q68) The density of a crystalline material is equal to the : Show Answer

Q69) Which of the following properties are common to liquids and amorphous solids ? Show Answer

Q70) What is co-ordination number ? The no. of the : Show Answer

Q71) In a semiconductor diode, the reserve biased current is due to drift of free electrons and holes caused by : Show Answer

Q72) Which one of the following shows correctly the input characteristics of a transistor in common base configuration ? Show Answer

Q73) In a semiconductor crystal, if the current flows due to breakage of crystal bonds, then the semiconductor is called : Show Answer

Q74) When two semiconductors of P and N-type are brought into contact, they form a P-N junction which acts like a : Show Answer

Q75) 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

Q76) On increasing the reverse bias to a large value in a P-N junction diode current : Show Answer

Q77) When N- type of semiconductor is heated Show Answer

Q78) How many NAND gates are used to form AND gate ? Show Answer

Q79) what are ripples ? Show Answer

Q80) The "FREE ELECTRON " model of metallic solid does not explain : Show Answer

Q81) Who was first to use Boolean algebra for describing the operation of logic gates ? Show Answer

Q82) Which gate is formed by inverting the output of AND gate ? Show Answer

Q83) Ice is an example of : Show Answer

Q84) 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

Q85) Energy bonds in solids are a consequence of : Show Answer

Q86) When aluminium is added as an impurity to silicon, then resulting material is : Show Answer

Q87) In junction diode, the holes are because of : Show Answer

Q88) 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

Q89) Which of the following is NOT equal to O in the Boolean algebra ? Show Answer

Q90) In the Boolean algebra which of the following is NOT equal to A ? Show Answer

Q91) The nature of binding for a crystal with alternate and evenly spaced positive and negative ions is : Show Answer

Q92) The energy gap between conduction band and valence band is order of 0.7 eV. It is a : Show Answer

Q93) In bcc crystal, the distance between any two nearest atom is Show Answer

Q94) What account for flow of charge carriers in forward and reserve biasing of silicon p-n diode ? Show Answer

Q95) The intrinsic semiconductor behaves as an insulator at : Show Answer

Q96) For a logic 0101 the waveform is : Show Answer

Q97) Which of the following figure represents an ideal diode characteristics ? Show Answer

Q98) The forward biased diode is : Show Answer

Q99) Which of the following when added as an impurity into the silicon, produces n- type semi - conductor : Show Answer

Q100) A current gain for a transistor working as CB amplifier is 0.96. If emitter current is 7.2 mA, then base current is : Show Answer

Q101) In a P-N junction : Show Answer

Q102) In Germanium crystal, impurity donor element have valency : Show Answer

Q103) At 0 K temp., a p-type semiconductor : Show Answer

Q104) The potential barrier in the depletion layer is due to : Show Answer

Q105) Barrier potential of a P- N junction diode does not depend on : Show Answer

Q106) Reverse bias applied on a junction diode : Show Answer

Q107) 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

Q108) Assertion : In a transistor the base is made thin.
Reason : A thin base makes the transistor stable. Show Answer

Q109) A n-p-n transistor conducts when : Show Answer

Q110) 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

Q111) Of the diodes shown in the following diagrams, which one is reserve biased ? Show Answer

Q112) 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

Q113) Which of the following logic gates is an universal gate ? Show Answer

Q114) 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

Q115) Application of a forward bias to a P-N junction : Show Answer

Q116) Zener diode is used for : Show Answer

Q117) A transistor oscillator using a resonant circuit was an inductor L and a capacitor C in series produce oscillations of frequency f. If L is double and C is changes to 4C, the frequency will be : Show Answer

Q118) When a P-N diode is reverse biased then : Show Answer

Q119) A light emitting diode (LED) has a voltage drop of 2 volt across it and passes a current of 10 mA when it operates with a 6 volt battery through a limiting resistor R. The value of R is : Show Answer

Q120) The output of a diode rectifier is : Show Answer

Q121) In intrinsic semiconductor at room temperature, number of electrons and holes are : Show Answer

Q122) Enetordy of a superconductor is : Show Answer

Q123) The amplification factor of a triode depends on the : Show Answer

Q124) A pentode can be used : Show Answer

Q125) A modulator is used for : Show Answer

Q126) Degree of modulation : Show Answer

Q127) The static amplification factor of a triode value depends upon : Show Answer

Q128) The fourth electrode in a tetrode is to : Show Answer

Q129) The input a.c current frequency to a full wave rectifier is v then the output frequency of the current is : Show Answer

Q130) 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

Q131) What is the minimum number of parameters required to describe a three dimension crystal system : Show Answer

Q132) The energy gab between the valence band and the conduction band for a material is 6 eV. The material is, Show Answer

Q133) 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

Q134) In a transistor in the common emitter mode : Show Answer

Q135) 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

Q136) The impurity atoms with which a pure silicon should be doped to make a p-type semiconductor is : Show Answer

Q137) At room temperature,a p-type semi conductor has : Show Answer

Q138) The least region in a transistor is : Show Answer

Q139) NAND gate is : Show Answer

Q140) In an NPN transistor the collector current is 24 mA. If 80% of electrons reach collector its base current in mA is : Show Answer

Q141) For a cubic crystal structure which one of the following relations indicating the cell characteristics is correct ? Show Answer

Q142) 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

Q143) 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

Q144) Which one of the following statement is FALSE ? Show Answer

Q145) In forward biasing of the p-n junction : Show Answer

Q146) If a small amount of antimony is added to germanium crystal : Show Answer

Q147) The co-ordination number for a body centred cubic cell is : Show Answer

Q148) The lattice parameter for a crystalline structure is 3.6 A. Atomic radius in simple cubic crystal is : Show Answer

Q149) The atomic radius for a face centred cubic cell of lattice parameter a is : Show Answer

Q150) In a transistor : Show Answer

Q151) Truth table of NOR gate is : Show Answer

Q152) The space lattice of diamond is : Show Answer

Q153) The conductivity of a semiconductor is given by Show Answer

Q154) A hole diffuses from the P-side to the N-side in a P-N junction. This means that : Show Answer

Q155) The number of molecules per unit cell in fcc lattice is : Show Answer

Q156) Which of the following types of binding produces crystals that are transparent to visible light and conduct electricity only at higher temperatures ? Show Answer

Q157) In case of diamond, the forbidden gap is about : Show Answer

Q158) Metallic solids are always opaque because : Show Answer

Q159) If r is the input resistance and R is the output resistance (R > r), the voltage gain in common emitter configuration is : Show Answer

Q160) If r is the input resistance and R is the output resistance (R > r), the voltage gain in common base configuration is : Show Answer

Q161) The ionization track of a subatomic particle can be photographed in : Show Answer

Q162) Rubber is an example of : Show Answer

Q163) Which of the following is not the property of a crystalline substance ? Show Answer

Q164) The minimum proportion of available volume which may be filled by hard spheres arranged in various structures is : Show Answer

Q165) Atoms of copper sulphate crystal are arranged in : Show Answer

Q166) 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

Q167) The atomic packing factor for a fcc cell is : Show Answer

Q168) Zener diode is used for Show Answer

Q169) When an impurity is doped into an intrinsic semiconductor the conductivity of the semiconductor Show Answer

Q170) A capacitor is to be used to provide smoothing for a half wave rectifier. In which of the following diagrams is capacitor correctly connected ? Show Answer

Q171) Silicon is a semiconductor. If a small amount of As is added to it, then its electrical conductivity Show Answer

Q172) An intrinsic - semiconductor at absolute zero of temperatures behaves as Show Answer

Q173) To obtain P - type Si semiconductor, we need to dope pure Si with Show Answer

Q174) If the forward voltage in a diode is increased, the width of the depletion region Show Answer

Q175) The impurity atom that should be added to Germanium to make its n - type is Show Answer

Q176) 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

Q177) Statement 1 : The conductivity of a semiconductor increases with rise of temperature.
Statement 2 : On rising temperature covalent bonds of semiconductor break.
Show Answer

Q178) Of the diodes shown in figure which one is reverse biased ? Show Answer

Q179) The dominant contribution to current comes from holes in case of Show Answer

Q180) A PN junction diode cannot be used Show Answer

Q181) Diffusion current in a p-n junction is grearer than the drift current in magnitude Show Answer

Q182) For germanium crystal, the forbidden energy gap in joule is Show Answer

Q183) 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

Q184) In an n-type semiconductor, donor valence band is Show Answer

Q185) A pure semiconductor has Show Answer

Q186) When the conductivity of a semiconductor is only due to breaking of covalent bonds, the semiconductor is called Show Answer

Q187) Reverse bias applied to a junction diode Show Answer

Q188) 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

Q189) 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

Q190) 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

Q191) 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

Q192) What will be the forward current at a forward voltage of 0.6 V ? Show Answer

Q193) What will be the increase in the current, if the voltage across the diode is increased to 0.7 V ? Show Answer

Q194) What is the dynamic resistance ? Show Answer

Q195) Which of the following is not analogue signal ? Show Answer

Q196) Refer to the circuit shown in figure. What inputs X and Y will produce a high output at R ? Show Answer

Q197) How many NAND gates are required to make an OR gate ? Show Answer

Q198) 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

Q199) Statement 1 : NOT gate is also called invertor circuit.
Statement 2 : NOT gate inverts the input order.
Show Answer

Q200) The circuit above behaves as Show Answer

Q201) If all the NOR gate in the circuits are replaced by NAND gates, the circuit would perform the logic operation of Show Answer

Q202) The output of OR gate is 1 Show Answer

Q203) The boolean expression for NAND gate is Show Answer

Q204) If A = 1 and B = 0, then A.A + B in the boolean expression is equal to Show Answer

Q205) Which of the following is the logic symbol of NAND gate ? Show Answer

Q206) If one terminal of an XOR gate is kept at 1, the output will be zero when the other terminal is at Show Answer

Q207) In boolean algebra, which of the following is not equal to zero Show Answer

Q208) Which of the following is not correct ? Show Answer

Q209) Identify the gate in box II Show Answer

Q210) Identify the gate in box III Show Answer

Q211) An AND gate can be prepared by repetitive use of Show Answer

Q212) The number of NAND gates required to make NOT gate is Show Answer

Q213) 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

Q214) The logic gate circuit is Show Answer

Q215) Which one of the following cirucits would give waveforms as given in the passage above Show Answer

Q216) When the forward bias voltage of a diode is changed from 0.6 V to 0.7 V, the current changes from 5 mA to
15 mA. Then its forward bias resistance is Show Answer

Q217) In an intrinsic semiconductor, the Fermi level is Show Answer

Q218) The potential in depletion layer is due to Show Answer

Q219) 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

Q220) In an intrinsic semiconductor,the Fermi level is Show Answer

Q221) Formation of covalent bonds in compounds exhibits Show Answer

Q222) The current gain of a transistor in common base mode is 0.995. the current gain of the same transistor in
common emitter mode is Show Answer

Q223) The temperature coefficient of resistance of a semiconductor Show Answer

Q224) Carbon, silicon and germanium have four valence electrons each. At room temperature which one of the
following statements is more appropriate? Show Answer

Q225) If a full wave rectifier circuit is operating from 50Hz mains, the fundamental frequency in the ripple will be Show Answer

Q226) The electrical circuit used to get smooth DC output from a rectifier circuit is called Show Answer

Q227) A piece of semiconductor is connected in series in an electric circuit. On increasing the temperature, the
current in the circuit will Show Answer

Q228) For a common emitter amplifier, the audio signal voltage across the collector resistance 2kΩ is 2 V. If the
current amplification factor of the transistor is 220, and the base resistance is 1.5 Ω, the input signal
voltage and base current are Show Answer

Q229) If the forward voltage in a semiconductor diode is changed from 0.5 V to 0.7 V, then the forward current
changes by 1.0 mA. The forward resistance of diode junction will be Show Answer

Q230) The temperature coefficient of resistance of semiconductor Show Answer

Q231) If no external voltage is applied across P-N junction,there would be Show Answer

Q232) The current gain of transistor base mode is 0.995. The current gain of same transistor is Show Answer

Q233) In CE mode,the input characteristics of transistor is the variation of Show Answer

Q234) Which of the following is a dichroic crystal Show Answer

Q235) Zener breakdown in a semi-conductor diode occurs when Show Answer

Q236) The difference in the variation of resistance with temperature in a metal and a semiconductor arises
essentially due to the difference in th Show Answer

Q237) The coordination number of hexagonal close packing (hcp) is Show Answer

Q238) The typical ionisation energy of a donor in silicon is Show Answer

Q239) Consider the following statements A and
B and identify the correct choice of the given answers
A. The width of the depletion layer in a
P - N junction diode increases in forward bias
B.In an intrinsic semiconductor the fermi energy level is exactly in the middle of the forbidden gap Show Answer

Q240) In N - type semiconductors, majority charge carriers are Show Answer

Q241) In the following,which one of the diodes is reversed biased? Show Answer

Q242) In a triode,cathode,grid and plate are at 0, -2, and 80V respectively,The electrons are emitted from the cathode with energy 3eV.The energy of the electron reaching the plate is Show Answer

Q243) Resistance of a semiconductor Show Answer

Q244) In a common emitter amplifier the input signal is applied across Show Answer

Q245) The phenomenon of thermionic emission was discovered by Show Answer

Q246) In depletion layer of unbiased p-n junction
Show Answer

Q247) Carbon,silicon and germanium have four valence electron each.At room temperature which one of the following statements is more appriciate? Show Answer

Q248) The output of NAND gate is 0 Show Answer

Q249) What is the name of level due to impurity atom in P -type in the forbidden gap Show Answer

Q250) Which of the following gates will have an output of 1. Show Answer

Q251) In N-type semiconductors,majority charge carriers are Show Answer

Q252) In the middle of the depletion layer of reverse biased p-n junction, the Show Answer

Q253) In the circuit of a triode value,there is no change in the plate current,when the plate potential is increased from 200 V and the grid potential is decreased from -0.5V to -1.3V.The amplification factor of value us Show Answer

Q254) In a triode amplifier ,the value of maximum gain is equal to Show Answer

Q255) P -type semiconductor is formed when

A. As impurity is mixed in Si.
B. Al impurity is mixed in Si.
C. B impurity is mixed in Ge.
D.P impurity is mixed in Ge. Show Answer

Q256) A piece of a semiconductor is connected in series in an electric circuit .On increasing the temperature ,the current in the circuit will Show Answer

Q257) A p-type material is electricity ................ Show Answer

Q258) Which of the following statement is not correct when a junction diode is forward bias? Show Answer

Q259) If forward voltage in a semiconductor diode is changed from 0.5V t 0.7V,then the forward current changes by 1.0 mA.the forward resistance of diode junction will be Show Answer

Q260) Any digital circuit can be realized by repetitive use of only Show Answer

Q261) In p-n junction, the barrier potential offers resistance to Show Answer

Q262) Would there any advantage
to adding n-type or p-type impurities in copper Show Answer

Q263) The co -ordination number of hexagonal close packing (hcp) is Show Answer

Q264) The typical ionization energy of a donor in silicon is Show Answer

Q265) Consider the following statement A and B and identify the correct choice of the given answers .
A.A width of the depletion layer in a P-N junction diode increases in forward bias

B.In an intrensic semiconductor the fermi level is exactly in the middle of the forbidden gap Show Answer

Q266) In an unbiased p-n junction Show Answer

Q267) In the presence of interspace charge at plate voltage of 200 v ,the current is 80 mA. Then the current in mA at 400 V will be Show Answer

Q268) Resistance of semiconductor Show Answer

Q269) In a transistor the base is Show Answer

Q270) Name of a p-n junction, which can be used as the regulator, is
Show Answer

Q271) A strip of copper and another of germanium are cooled from room temperature to 80 K the resistance of Show Answer

Q272) Number of secondary electrons emitted per number of primary electrons depends on Show Answer

Q273) Wires P and Q have the same resistance at ordinary (room) temperature. When heated, resistance of P
increases and that of Q decreases. We conclude that Show Answer

Q274) Diode valve is discovered by Show Answer

Q275) Current gain in common base configuration is less than 1 because Show Answer

Q276) Digital circuit can be made by repetitive use of this gate Show Answer

Q277) The value of ripple factor for full wave rectifier is Show Answer

Q278) The valence band and conduction band of a solid overlap at low temperature, the solid may be Show Answer

Q279) The ratio of slopes of anode characteristics and mutual characteristic curves is said to be Show Answer

Q280) The coordination number of body centred crystal is
Show Answer

Q281) To a germanium sample, traces of gallium are added as an impurity. The resultant sample would behave
like Show Answer

Q282) P-N junction is said to be forward biased, when Show Answer

Q283) Identify the true statement for OR gate
Show Answer

Q284) Barrier potential of a p-n junction diode does not depend on Show Answer

Q285) The part of a transistor which is heavily doped to produce a large number of majority carriers is Show Answer

Q286) In a P-type semiconductor, the acceptor impurity produces an energy level Show Answer

Q287) If the output of a logic gate is 0 when all its inputs are at logic
1, then the gate is either Show Answer

Q288) In LED visible light is produced by
Show Answer

Q289) Due to S.C.R. in vacuum tube Show Answer

Q290) The Fermi level of an intrinsic semiconductor is pinned at the centre of the band gap. The probability of
occupation of the highest electron state in valence band at room temperature, will be
Show Answer

Q291) Plate current in a diode depends Show Answer

Q292) The saturation current in a diode valve is governed by Show Answer

Q293) In order to prepare a p-type semiconductor, pure silicon can be doped with Show Answer

Q294) In a transistor the collector current is always less than the emitter current because Show Answer

Q295) 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

Q296) A photodetector used to detect the wavelength of 1700nm,has energy gap of about Show Answer

Q297) A piece of copper and another of germanium are cooled from room temperature to 77K ,the resistance of Show Answer

Q298) which of the following has negative temperature coefficient of resistance. Show Answer

Q299) In an n-type semiconductor, the fermi energy level lies Show Answer

Q300) In colpit oscillator the feedback network consists of Show Answer

Q301) Which of the following is amorphous substance? Show Answer

Q302) A metallic surface with work function of 2 eV, on heating to a temperature of 800 K gives an emission
current of 1 mA. If another metallic surface having the same surface area, same emission constant but
work function 4 eV is heated to a temperature of 1600 K, then the emission current will be Show Answer

Q303) When boron is added as an impurity to silicon, the resulting material is
Show Answer

Q304) The PN junction diode is used as
Show Answer

Q305) The typical ionisation energy of a donar in silicon is
Show Answer

Q306) Which circuit will not show current in ammeter
Show Answer

Q307) The logic behind ‘NOR’ gate is that it gives Show Answer

Q308) How many NAND gates are required to form an AND gate? Show Answer

Q309) A solid which is not transparent to visible light and whose electrical conductivity increases with
temperature is formed by Show Answer

Q310) The output of OR gate is 1 Show Answer

Q311) A transistor is used as an amplifier in CB mode with a load resistance of 5 k Ω. The current gain of amplifier is 0.98 and the input resistance is 70 Ω, the voltage gain and power gain respectively are
Show Answer

Q312) The current gain α of a transistor in common base mode is 0.995. Its gain β in the common emitter mode is
Show Answer

Q313) In a n-p-n transistor, the collector current is 10mA. If 90% of the electrons emitted reach the collector,
then the emitter current will be Show Answer

Q314) A pure semiconductor behaves slightly as a conductor at Show Answer

Q315) The nature of binding for a crystal with alternate and evenly spaced positive and negative ions is Show Answer

Q316) Doping of a semiconductor (with small traces of impurity atoms) generally changes the resistivity as
follows Show Answer

Q317) Radiowaves of constant amplitude can be generated with Show Answer

Q318) When the plate voltage of a triode is 150V, its cut-off voltage is −5 V. On increasing the plate voltage to 200
V, the cut-off voltage can be Show Answer

Q319) The mutual characteristic of triode is Show Answer

Q320) In a forward biased p-n junction diode, the potential barrier in the depletion region is of the form Show Answer

Q321) What makes the crystalline solids have a sharp melting point? Show Answer

Q322) Symbolic representation of photodiode is Show Answer

Q323) Choose the correct statement Show Answer

Q324) The current gain of a common base transistor circuit is 0.96. On changing the emitter current by 10.0 mA,
the change in the base current will be Show Answer

Q325) The manifestation of band structure in solids is due to decreases the majority charge carries Show Answer

Q326) A crystal diode is a Show Answer

Q327) Coating of strontium oxide on tungsten cathode in a valve is good for thermionic emission because Show Answer

Q328) In an NPN transistor the collector current is 24 mA. If 80% of electrons reach collector its base current in mA is Show Answer

Q329) Of the following which relation is true? Show Answer

Q330) In case of a semiconductor, which of the following statement is wrong
Show Answer

Q331) Which of the following logic gate is an universal gate
Show Answer

Q332) The correct curve between potential (V) and distance (d) near p - n junction is
Show Answer

Q333) Reverse bias applied to a p-n junction diode
Show Answer

Q334) Consider an NPN transistor amplifier in common-emitter configuration. The current gain of the transistor is 100. If the collector current changes by 1 mA, what will be the change in emitter current Show Answer

Q335) The electrical conductivity of an intrinsic semiconductor at 0 K is Show Answer

Q336) Change in temperature
Show Answer

Q337) The energy of radiation emitted by LED is
Show Answer

Q338) In a semiconductor Show Answer

Q339) In a 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

Q340) In p-type semiconductors, conduction is due to
Show Answer

Q341) When plate voltage in diode valve is increased from 100 volt to 150 volt then plate current increases from 7.5 mA to 12 mA. The dynamic plate resistance will be
Show Answer

Q342) The collector supply voltage is 6 V and the voltage drop across a resistor of 600 Ω in the collector circuit is 0.6 V, in a transistor connector in common emitter mode. If the current gain is 20, the base current is Show Answer

Q343) In a p-n junction diode Show Answer

Q344) An alternating current can be converted into direct current by a Show Answer

Q345) Electronic configuration of germanium is 2, 8, 18 and 4. To make it extrinsic semiconductor small quantity of antimony is added. Show Answer

Q346) In BJT, maximum current flows in which of the following? Show Answer

Q347) A solid reflects incident light and its electrical conductivity decreases with temperature. The binding in
this solid is Show Answer

Q348) When p-n junction diode is forward biased then
Show Answer

Q349) Pick out the statement which is not correct Show Answer

Q350) When a solid with a band gap has a donor level just below its empty energy band, the solid is Show Answer

Q351) For a transistor amplifier, the voltage gain Show Answer

Q352) A piece of copper and other of germanium are cooled from the room temperature to 80 K, then
Show Answer

Q353) Identify the property which is not characteristic for a semiconductor? Show Answer

Q354) Which of the following is forward biased? Show Answer

Q355) The curve between charge density and distance near P-N junction will be Show Answer

Q356) Semiconductor is damaged by the strong current due to Show Answer

Q357) Diode is used as a/an Show Answer

Q358) What is the coordination number of sodium ions in the case of sodium chloride structure? Show Answer

Q359) A transistor oscillator is
(i) An amplifier with positive feedback
(ii) An amplifier with reduced gain
(iii) The one in which DC supply energy is converted into AC output energy. Then Show Answer

Q360) In silicon when phosphorus is doped...................is formed. Show Answer

Q361) When a p-n junction diode is reverse biased, then Show Answer

Q362) when phosphorus and antimony are mixed in germanium,then Show Answer

Q363) Atomic packing factor for a face centred cubic cells Show Answer

Q364) For a given plate-voltage, the plate current in a triode is maximum when the potential of Show Answer

Q365) In a diode,when there is saturation current,the plate resistance will be Show Answer

Q366) In an experiment the saturation in the plate current in a diode is observed at 240V. But a student still wants to increase the plate current. It can be done ,if Show Answer

Q367) The emitter-base junction of a transistor is ............... biased while the collector-base junction is ..................
biased Show Answer

Q368) The maximum efficiency of full wave rectifier is Show Answer

Q369) The expected energy of the electrons at absolute zero is called Show Answer

Q370) A transistor has a base current of 1 mA and emitter current 90 mA. The collector current will be Show Answer

Q371) Current gain in common emitter configuration is more than 1 becomes Show Answer

Q372) Avalanche breakdown in a p-n junction diode is due to Show Answer

Q373) Resistivity of a semiconductor depends on Show Answer

Q374) For an insulator the forbidden energy gap is Show Answer

Q375) In semiconductors at a room temperature Show Answer

Q376) The ionic bond is absent in Show Answer

Q377) Different voltages are applied across a p-n junction and the currents are measured from each value. Which of the following graphs is obtained between voltage and current?
Show Answer

Q378) How many NAND gates are used in an OR gate? Show Answer

Q379) The electrical resistance of depletion layer is large because Show Answer

Q380) If control grid is made negative, then the plate current will Show Answer

Q381) Zener breakdown takes place if Show Answer

Q382) In a P-type semiconductor Show Answer

Q383) Bonding in a germanium crystal (semi-conductor) is Show Answer

Q384) The binary number 10111 is equivalent to the decimal number
Show Answer

Q385) if the forward voltage in a diode is increased, the width of the depletion region
Show Answer

Q386) The n-type semiconductors are obtained, when germanium is doped with
Show Answer

Q387) In forward bias, the width of potential barrier in a P-N junction diode
Show Answer

Q388) In a P-N junction diode if
P region is heavily doped than n region then the depletion layer is Show Answer

Q389) A n-p-n transistor having a.c. current gain of 50 is to be used to make an amplifier of power gain of 300. What will be the voltage gain of the amplifier Show Answer

Q390) Electric conduction in semi-conductor takes place due to
Show Answer

Q391) For germanium crystal, the forbidden energy gap in joules is
Show Answer

Q392) In an insulator, the forbidden energy gap between the valance band and conduction band is of the order of Show Answer

Q393) The ratio of work functions and temperatures of two emitters are 1 : 2, then the ratio of current densities obtained by them will be Show Answer

Q394) In P-N junction, avalanche current flows in circuit when biasing is
Show Answer

Q395) In a P-type semi-conductor, germanium is dopped with Show Answer

Q396) The gate for which output is high, if at least one input is low?
Show Answer

Q397) The phase
difference between input and output voltages of a CE circuit is Show Answer

Q398) To a germanium crystal equal number of aluminium and indium atoms are added. Then
Show Answer

Q399) In a common base transistor circuit, the current gain is 0.98. On changing emitter current by 5.00 mA, the change in collector current is Show Answer

Q400) While using triode as
an amplifier, we avoid making the grid positive because Show Answer

Q401) Why do we prefer indirectly heated cathode to the directly heated cathode? Show Answer

Q402) Which of the following is not a process involved in fabrication of IC
Show Answer

Q403) p-type semiconductor are
Show Answer

Q404) The temperature of germanium is decreased from room temperature to 100 K, the resistance of germanium Show Answer

Q405) An n-type semiconductor is Show Answer

Q406) Biaxial crystal among the following is
Show Answer

Q407) 14× 10¹⁵electrons reach the anode per second. If the power consumed is 448milli watts then the plate
(anode) voltage is
Show Answer

Q408) The ripple factor in a half wave rectifier is
Show Answer

Q409) The reverse saturation of p-n diode
Show Answer

Q410) The phase difference between input and output voltages of a CE circuit is
Show Answer

Q411) Diode is not considered as linear device because Show Answer

Q412) While using triode as an amplifier, we avoid making the grid positive because,
Show Answer

Q413) Least doped region in a transistor Show Answer

Q414) The main cause of zener breakdown is Show Answer

Q415) A Si and a Ge diode has identical physical dimensions. The band gap in Si is larger than that in Ge. An identical reverse bias is applied across the diodes Show Answer

Q416) Why is there sudden increase in current in zener diode? Show Answer

Q417) C and Si both have same lattice structure, having 4 bonding electrons in each. However, C is insulator where as Si is intrinsic semiconductor. This is because Show Answer

Q418) Which of the following materials in non crystalline
Show Answer

Q419) The addition of antimony atoms to a sample of intrinsic germanium transforms it to a material which is
Show Answer

Q420) A semiconductor device is connected in a series circuit with a battery and a resistance. A current is found
to pass through the circuit. If the polarity of the battery is revered, the current drops almost to zero. The
device may be Show Answer

Q421) The voltage gain of an amplifier with 9% negative feedback is 10. The voltage gain without feedback will be
Show Answer

Q422) The charge on a hole is equal to the charge of Show Answer

Q423) 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

Q424) Regarding a semiconductor which one of the following is wrong Show Answer

Q425) Bonds in semiconductor are Show Answer

Q426) The temperature coefficient of a zener mechanism is Show Answer

Q427) In the presence of space charge in the diode valve the plate current is 10mA at the plate voltage 50V. Then the plate current at plate voltage 200 V will be Show Answer

Q428) Which of the following is not equal to 1 in Boolean algebra? Show Answer

Q429) The temperature coefficient of resistance of a conductor is Show Answer

Q430) Which one of the following is the weakest kind of bonding in solids Show Answer

Q431) Donor type impurity is found in Show Answer

Q432) The Binary Coded Decimal (BCD) equivalent of 429 is Show Answer

Q433) In a transistor in common-emitter configuration, the ratio of power gain to voltage gain is Show Answer

Q434) In breakdown region, a zener diode behaves as a Show Answer

Q435) A triode whose mutual conductance is 2.5 m A/volt and anode resistance is 20 killo ohm, is used as an
amplifier whose amplification is 10. The resistance connected in plate circuit will be
Show Answer

Q436) Avalanche breakdown is due to Show Answer

Q437) An oscillator in nothing but an amplifier with Show Answer

Q438) In order to rectify an alternating current one uses a Show Answer

Q439) Metallic solids are always opaque because Show Answer

Q440) The coordination number of simple cubic crystal is Show Answer

Q441) Energy bands in solids are a consequence of Show Answer

Q442) Which of the following materials is the best conductor of electricity Show Answer

Q443) Which one is in forward bias Show Answer

Q444) Which of the energy band diagrams shown in the figure corresponds to that of a semiconductor? Show Answer

Q445) The probability of electrons to be found in the conduction band of an intrinsic semiconductor at a finite
temperature Show Answer

Q446) In a properly biased transistor Show Answer

Q447) Which represents NAND gate Show Answer

Q448) The resistivity of a semiconductor at room temperature is in between Show Answer

Q449) When the electrical of a semi- conductor is due to the breaking of its covalent bonds, then the semiconductor is said to be Show Answer

Q450) Silicon is a semiconductor. If a small amount of As is added to it, then its electrical conductivity Show Answer

Q451) 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

Q452) Identify the incorrect statement regarding a superconducting wire Show Answer

Q453) The current gain of a transistor in the common base mode is 0.9. If the change in the emitter current is 5
mA, the change in the collector current will be Show Answer

Q454) To write the decimal number 37 in binary, how many binary digits are required Show Answer

Q455) For a cubic crystal structure which one of the following relations indicating the cell characteristic is
correct? Show Answer

Q456) Zener diode is used as Show Answer

Q457) When the forward biased voltage of a diode is changed from 0.6V to 0.7V,the current changes from 5mA to 15mA,then forward bias resistance is Show Answer

Q458) In triode,cathode,grid and plate are at 0,-2 and 80V respectively.The electrons are emitted from the cathode with energy 3 eV.The electrons reaching the plate is Show Answer

Q459) When germanium is doped with phosphorus, the doped material has Show Answer

Q460) Which of these is unipolar transistor Show Answer