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

Q65) Quartz is a crystalline solid because it is : Show Answer

Q66) Silver has fcc structure. If the interatomic spacing is 2.888 A, the lattice constant is : Show Answer

Q67) The density of a crystalline material is equal to the : Show Answer

Q68) Which of the following properties are common to liquids and amorphous solids ? Show Answer

Q69) What is co-ordination number ? The no. of the : Show Answer

Q70) In a semiconductor diode, the reserve biased current is due to drift of free electrons and holes caused by : Show Answer

Q71) Which one of the following shows correctly the input characteristics of a transistor in common base configuration ? Show Answer

Q72) In a semiconductor crystal, if the current flows due to breakage of crystal bonds, then the semiconductor is called : Show Answer

Q73) When two semiconductors of P and N-type are brought into contact, they form a P-N junction which acts like a : Show Answer

Q74) 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

Q75) On increasing the reverse bias to a large value in a P-N junction diode current : Show Answer

Q76) When N- type of semiconductor is heated Show Answer

Q77) How many NAND gates are used to form AND gate ? Show Answer

Q78) what are ripples ? Show Answer

Q79) The "FREE ELECTRON " model of metallic solid does not explain : Show Answer

Q80) Who was first to use Boolean algebra for describing the operation of logic gates ? Show Answer

Q81) Which gate is formed by inverting the output of AND gate ? Show Answer

Q82) Ice is an example of : Show Answer

Q83) 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

Q84) Energy bonds in solids are a consequence of : Show Answer

Q85) When aluminium is added as an impurity to silicon, then resulting material is : Show Answer

Q86) In junction diode, the holes are because of : Show Answer

Q87) 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

Q88) Which of the following is NOT equal to O in the Boolean algebra ? Show Answer

Q89) In the Boolean algebra which of the following is NOT equal to A ? Show Answer

Q90) The nature of binding for a crystal with alternate and evenly spaced positive and negative ions is : Show Answer

Q91) The energy gap between conduction band and valence band is order of 0.7 eV. It is a : Show Answer

Q92) In bcc crystal, the distance between any two nearest atom is Show Answer

Q93) What account for flow of charge carriers in forward and reserve biasing of silicon p-n diode ? Show Answer

Q94) The intrinsic semiconductor behaves as an insulator at : Show Answer

Q95) For a logic 0101 the waveform is : Show Answer

Q96) Which of the following figure represents an ideal diode characteristics ? Show Answer

Q97) The forward biased diode is : Show Answer

Q98) Which of the following when added as an impurity into the silicon, produces n- type semi - conductor : Show Answer

Q99) 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

Q100) In a P-N junction : Show Answer

Q101) In Germanium crystal, impurity donor element have valency : Show Answer

Q102) At 0 K temp., a p-type semiconductor : Show Answer

Q103) The potential barrier in the depletion layer is due to : Show Answer

Q104) Barrier potential of a P- N junction diode does not depend on : Show Answer

Q105) Reverse bias applied on a junction diode : Show Answer

Q106) 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

Q107) Assertion : In a transistor the base is made thin.
Reason : A thin base makes the transistor stable. Show Answer

Q108) A n-p-n transistor conducts when : Show Answer

Q109) 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

Q110) Of the diodes shown in the following diagrams, which one is reserve biased ? Show Answer

Q111) 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

Q112) Which of the following logic gates is an universal gate ? Show Answer

Q113) 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

Q114) Application of a forward bias to a P-N junction : Show Answer

Q115) Zener diode is used for : Show Answer

Q116) 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

Q117) When a P-N diode is reverse biased then : Show Answer

Q118) 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

Q119) The output of a diode rectifier is : Show Answer

Q120) In intrinsic semiconductor at room temperature, number of electrons and holes are : Show Answer

Q121) Enetordy of a superconductor is : Show Answer

Q122) The amplification factor of a triode depends on the : Show Answer

Q123) A pentode can be used : Show Answer

Q124) A modulator is used for : Show Answer

Q125) Degree of modulation : Show Answer

Q126) The static amplification factor of a triode value depends upon : Show Answer

Q127) The fourth electrode in a tetrode is to : Show Answer

Q128) The input a.c current frequency to a full wave rectifier is v then the output frequency of the current is : Show Answer

Q129) 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

Q130) What is the minimum number of parameters required to describe a three dimension crystal system : Show Answer

Q131) The energy gab between the valence band and the conduction band for a material is 6 eV. The material is, Show Answer

Q132) 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

Q133) In a transistor in the common emitter mode : Show Answer

Q134) 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

Q135) The impurity atoms with which a pure silicon should be doped to make a p-type semiconductor is : Show Answer

Q136) At room temperature,a p-type semi conductor has : Show Answer

Q137) The least region in a transistor is : Show Answer

Q138) NAND gate is : Show Answer

Q139) In an NPN transistor the collector current is 24 mA. If 80% of electrons reach collector its base current in mA is : Show Answer

Q140) For a cubic crystal structure which one of the following relations indicating the cell characteristics is correct ? Show Answer

Q141) 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

Q142) 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

Q143) Which one of the following statement is FALSE ? Show Answer

Q144) In forward biasing of the p-n junction : Show Answer

Q145) If a small amount of antimony is added to germanium crystal : Show Answer

Q146) The co-ordination number for a body centred cubic cell is : Show Answer

Q147) The lattice parameter for a crystalline structure is 3.6 A. Atomic radius in simple cubic crystal is : Show Answer

Q148) The atomic radius for a face centred cubic cell of lattice parameter a is : Show Answer

Q149) In a transistor : Show Answer

Q150) Truth table of NOR gate is : Show Answer

Q151) The space lattice of diamond is : Show Answer

Q152) The conductivity of a semiconductor is given by Show Answer

Q153) A hole diffuses from the P-side to the N-side in a P-N junction. This means that : Show Answer

Q154) The number of molecules per unit cell in fcc lattice is : Show Answer

Q155) Which of the following types of binding produces crystals that are transparent to visible light and conduct electricity only at higher temperatures ? Show Answer

Q156) In case of diamond, the forbidden gap is about : Show Answer

Q157) Metallic solids are always opaque because : Show Answer

Q158) If r is the input resistance and R is the output resistance (R > r), the voltage gain in common emitter configuration is : Show Answer

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

Q160) The ionization track of a subatomic particle can be photographed in : Show Answer

Q161) Rubber is an example of : Show Answer

Q162) Which of the following is not the property of a crystalline substance ? Show Answer

Q163) The minimum proportion of available volume which may be filled by hard spheres arranged in various structures is : Show Answer

Q164) Atoms of copper sulphate crystal are arranged in : Show Answer

Q165) 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

Q166) The atomic packing factor for a fcc cell is : Show Answer

Q167) Zener diode is used for Show Answer

Q168) When an impurity is doped into an intrinsic semiconductor the conductivity of the semiconductor Show Answer

Q169) 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

Q170) Silicon is a semiconductor. If a small amount of As is added to it, then its electrical conductivity Show Answer

Q171) An intrinsic - semiconductor at absolute zero of temperatures behaves as Show Answer

Q172) To obtain P - type Si semiconductor, we need to dope pure Si with Show Answer

Q173) If the forward voltage in a diode is increased, the width of the depletion region Show Answer

Q174) The impurity atom that should be added to Germanium to make its n - type is Show Answer

Q175) 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

Q176) Statement 1 : The conductivity of a semiconductor increases with rise of temperature.
Statement 2 : On rising temperature covalent bonds of semiconductor break.
Show Answer

Q177) Of the diodes shown in figure which one is reverse biased ? Show Answer

Q178) The dominant contribution to current comes from holes in case of Show Answer

Q179) A PN junction diode cannot be used Show Answer

Q180) Diffusion current in a p-n junction is grearer than the drift current in magnitude Show Answer

Q181) For germanium crystal, the forbidden energy gap in joule is Show Answer

Q182) 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

Q183) In an n-type semiconductor, donor valence band is Show Answer

Q184) A pure semiconductor has Show Answer

Q185) When the conductivity of a semiconductor is only due to breaking of covalent bonds, the semiconductor is called Show Answer

Q186) Reverse bias applied to a junction diode Show Answer

Q187) 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

Q188) 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

Q189) 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

Q190) 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

Q191) What will be the forward current at a forward voltage of 0.6 V ? Show Answer

Q192) What will be the increase in the current, if the voltage across the diode is increased to 0.7 V ? Show Answer

Q193) What is the dynamic resistance ? Show Answer

Q194) Which of the following is not analogue signal ? Show Answer

Q195) Refer to the circuit shown in figure. What inputs X and Y will produce a high output at R ? Show Answer

Q196) How many NAND gates are required to make an OR gate ? Show Answer

Q197) 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

Q198) Statement 1 : NOT gate is also called invertor circuit.
Statement 2 : NOT gate inverts the input order.
Show Answer

Q199) The circuit above behaves as Show Answer

Q200) If all the NOR gate in the circuits are replaced by NAND gates, the circuit would perform the logic operation of Show Answer

Q201) The boolean expression for NAND gate is Show Answer

Q202) If A = 1 and B = 0, then A.A + B in the boolean expression is equal to Show Answer

Q203) Which of the following is the logic symbol of NAND gate ? Show Answer

Q204) If one terminal of an XOR gate is kept at 1, the output will be zero when the other terminal is at Show Answer

Q205) In boolean algebra, which of the following is not equal to zero Show Answer

Q206) Which of the following is not correct ? Show Answer

Q207) Identify the gate in box II Show Answer

Q208) Identify the gate in box III Show Answer

Q209) An AND gate can be prepared by repetitive use of Show Answer

Q210) The number of NAND gates required to make NOT gate is Show Answer

Q211) 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

Q212) The logic gate circuit is Show Answer

Q213) Which one of the following cirucits would give waveforms as given in the passage above Show Answer

Q214) 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

Q215) In an intrinsic semiconductor, the Fermi level is Show Answer

Q216) The potential in depletion layer is due to Show Answer

Q217) 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

Q218) In an intrinsic semiconductor,the Fermi level is Show Answer

Q219) Formation of covalent bonds in compounds exhibits Show Answer

Q220) 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

Q221) The temperature coefficient of resistance of a semiconductor Show Answer

Q222) Carbon, silicon and germanium have four valence electrons each. At room temperature which one of the
following statements is more appropriate? Show Answer

Q223) If a full wave rectifier circuit is operating from 50Hz mains, the fundamental frequency in the ripple will be Show Answer

Q224) The electrical circuit used to get smooth DC output from a rectifier circuit is called Show Answer

Q225) A piece of semiconductor is connected in series in an electric circuit. On increasing the temperature, the
current in the circuit will Show Answer

Q226) 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

Q227) 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

Q228) The temperature coefficient of resistance of semiconductor Show Answer

Q229) If no external voltage is applied across P-N junction,there would be Show Answer

Q230) The current gain of transistor base mode is 0.995. The current gain of same transistor is Show Answer

Q231) In CE mode,the input characteristics of transistor is the variation of Show Answer

Q232) Which of the following is a dichroic crystal Show Answer

Q233) Zener breakdown in a semi-conductor diode occurs when Show Answer

Q234) 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

Q235) The coordination number of hexagonal close packing (hcp) is Show Answer

Q236) The typical ionisation energy of a donor in silicon is Show Answer

Q237) 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

Q238) In N - type semiconductors, majority charge carriers are Show Answer

Q239) In the following,which one of the diodes is reversed biased? Show Answer

Q240) 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

Q241) Resistance of a semiconductor Show Answer

Q242) In a common emitter amplifier the input signal is applied across Show Answer

Q243) The phenomenon of thermionic emission was discovered by Show Answer

Q244) In depletion layer of unbiased p-n junction
Show Answer

Q245) Carbon,silicon and germanium have four valence electron each.At room temperature which one of the following statements is more appriciate? Show Answer

Q246) The output of NAND gate is 0 Show Answer

Q247) What is the name of level due to impurity atom in P -type in the forbidden gap Show Answer

Q248) Which of the following gates will have an output of 1. Show Answer

Q249) In N-type semiconductors,majority charge carriers are Show Answer

Q250) In the middle of the depletion layer of reverse biased p-n junction, the Show Answer

Q251) 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

Q252) In a triode amplifier ,the value of maximum gain is equal to Show Answer

Q253) 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

Q254) 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

Q255) A p-type material is electricity ................ Show Answer

Q256) Which of the following statement is not correct when a junction diode is forward bias? Show Answer

Q257) 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

Q258) Any digital circuit can be realized by repetitive use of only Show Answer

Q259) In p-n junction, the barrier potential offers resistance to Show Answer

Q260) Would there any advantage
to adding n-type or p-type impurities in copper Show Answer

Q261) The co -ordination number of hexagonal close packing (hcp) is Show Answer

Q262) The typical ionization energy of a donor in silicon is Show Answer

Q263) 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

Q264) In an unbiased p-n junction Show Answer

Q265) 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

Q266) Resistance of semiconductor Show Answer

Q267) In a transistor the base is Show Answer

Q268) Name of a p-n junction, which can be used as the regulator, is
Show Answer

Q269) A strip of copper and another of germanium are cooled from room temperature to 80 K the resistance of Show Answer

Q270) Number of secondary electrons emitted per number of primary electrons depends on Show Answer

Q271) 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

Q272) Diode valve is discovered by Show Answer

Q273) Current gain in common base configuration is less than 1 because Show Answer

Q274) Digital circuit can be made by repetitive use of this gate Show Answer

Q275) The value of ripple factor for full wave rectifier is Show Answer

Q276) The valence band and conduction band of a solid overlap at low temperature, the solid may be Show Answer

Q277) The ratio of slopes of anode characteristics and mutual characteristic curves is said to be Show Answer

Q278) The coordination number of body centred crystal is
Show Answer

Q279) To a germanium sample, traces of gallium are added as an impurity. The resultant sample would behave
like Show Answer

Q280) P-N junction is said to be forward biased, when Show Answer

Q281) Identify the true statement for OR gate
Show Answer

Q282) Barrier potential of a p-n junction diode does not depend on Show Answer

Q283) The part of a transistor which is heavily doped to produce a large number of majority carriers is Show Answer

Q284) In a P-type semiconductor, the acceptor impurity produces an energy level Show Answer

Q285) If the output of a logic gate is 0 when all its inputs are at logic
1, then the gate is either Show Answer

Q286) In LED visible light is produced by
Show Answer

Q287) Due to S.C.R. in vacuum tube Show Answer

Q288) 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

Q289) Plate current in a diode depends Show Answer

Q290) The saturation current in a diode valve is governed by Show Answer

Q291) In order to prepare a p-type semiconductor, pure silicon can be doped with Show Answer

Q292) In a transistor the collector current is always less than the emitter current because Show Answer

Q293) 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

Q294) A photodetector used to detect the wavelength of 1700nm,has energy gap of about Show Answer

Q295) A piece of copper and another of germanium are cooled from room temperature to 77K ,the resistance of Show Answer

Q296) which of the following has negative temperature coefficient of resistance. Show Answer

Q297) In an n-type semiconductor, the fermi energy level lies Show Answer

Q298) In colpit oscillator the feedback network consists of Show Answer

Q299) Which of the following is amorphous substance? Show Answer

Q300) 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

Q301) When boron is added as an impurity to silicon, the resulting material is
Show Answer

Q302) The PN junction diode is used as
Show Answer

Q303) The typical ionisation energy of a donar in silicon is
Show Answer

Q304) Which circuit will not show current in ammeter
Show Answer

Q305) The logic behind ‘NOR’ gate is that it gives Show Answer

Q306) How many NAND gates are required to form an AND gate? Show Answer

Q307) A solid which is not transparent to visible light and whose electrical conductivity increases with
temperature is formed by Show Answer

Q308) The output of OR gate is 1 Show Answer

Q309) 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

Q310) 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

Q311) 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

Q312) A pure semiconductor behaves slightly as a conductor at Show Answer

Q313) The nature of binding for a crystal with alternate and evenly spaced positive and negative ions is Show Answer

Q314) Doping of a semiconductor (with small traces of impurity atoms) generally changes the resistivity as
follows Show Answer

Q315) Radiowaves of constant amplitude can be generated with Show Answer

Q316) 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

Q317) The mutual characteristic of triode is Show Answer

Q318) In a forward biased p-n junction diode, the potential barrier in the depletion region is of the form Show Answer

Q319) What makes the crystalline solids have a sharp melting point? Show Answer

Q320) Symbolic representation of photodiode is Show Answer

Q321) Choose the correct statement Show Answer

Q322) 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

Q323) The manifestation of band structure in solids is due to decreases the majority charge carries Show Answer

Q324) A crystal diode is a Show Answer

Q325) Coating of strontium oxide on tungsten cathode in a valve is good for thermionic emission because Show Answer

Q326) In an NPN transistor the collector current is 24 mA. If 80% of electrons reach collector its base current in mA is Show Answer

Q327) Of the following which relation is true? Show Answer

Q328) In case of a semiconductor, which of the following statement is wrong
Show Answer

Q329) Which of the following logic gate is an universal gate
Show Answer

Q330) The correct curve between potential (V) and distance (d) near p - n junction is
Show Answer

Q331) Reverse bias applied to a p-n junction diode
Show Answer

Q332) 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

Q333) The electrical conductivity of an intrinsic semiconductor at 0 K is Show Answer

Q334) Change in temperature
Show Answer

Q335) The energy of radiation emitted by LED is
Show Answer

Q336) In a semiconductor Show Answer

Q337) 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

Q338) In p-type semiconductors, conduction is due to
Show Answer

Q339) 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

Q340) 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

Q341) In a p-n junction diode Show Answer

Q342) An alternating current can be converted into direct current by a Show Answer

Q343) Electronic configuration of germanium is 2, 8, 18 and 4. To make it extrinsic semiconductor small quantity of antimony is added. Show Answer

Q344) In BJT, maximum current flows in which of the following? Show Answer

Q345) A solid reflects incident light and its electrical conductivity decreases with temperature. The binding in
this solid is Show Answer

Q346) When p-n junction diode is forward biased then
Show Answer

Q347) Pick out the statement which is not correct Show Answer

Q348) When a solid with a band gap has a donor level just below its empty energy band, the solid is Show Answer

Q349) For a transistor amplifier, the voltage gain Show Answer

Q350) A piece of copper and other of germanium are cooled from the room temperature to 80 K, then
Show Answer

Q351) Identify the property which is not characteristic for a semiconductor? Show Answer

Q352) Which of the following is forward biased? Show Answer

Q353) The curve between charge density and distance near P-N junction will be Show Answer

Q354) Semiconductor is damaged by the strong current due to Show Answer

Q355) Diode is used as a/an Show Answer

Q356) What is the coordination number of sodium ions in the case of sodium chloride structure? Show Answer

Q357) 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

Q358) In silicon when phosphorus is doped...................is formed. Show Answer

Q359) When a p-n junction diode is reverse biased, then Show Answer

Q360) when phosphorus and antimony are mixed in germanium,then Show Answer

Q361) Atomic packing factor for a face centred cubic cells Show Answer

Q362) For a given plate-voltage, the plate current in a triode is maximum when the potential of Show Answer

Q363) In a diode,when there is saturation current,the plate resistance will be Show Answer

Q364) 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

Q365) The emitter-base junction of a transistor is ............... biased while the collector-base junction is ..................
biased Show Answer

Q366) The maximum efficiency of full wave rectifier is Show Answer

Q367) The expected energy of the electrons at absolute zero is called Show Answer

Q368) A transistor has a base current of 1 mA and emitter current 90 mA. The collector current will be Show Answer

Q369) Current gain in common emitter configuration is more than 1 becomes Show Answer

Q370) Avalanche breakdown in a p-n junction diode is due to Show Answer

Q371) Resistivity of a semiconductor depends on Show Answer

Q372) For an insulator the forbidden energy gap is Show Answer

Q373) In semiconductors at a room temperature Show Answer

Q374) The ionic bond is absent in Show Answer

Q375) 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

Q376) How many NAND gates are used in an OR gate? Show Answer

Q377) The electrical resistance of depletion layer is large because Show Answer

Q378) If control grid is made negative, then the plate current will Show Answer

Q379) Zener breakdown takes place if Show Answer

Q380) In a P-type semiconductor Show Answer

Q381) Bonding in a germanium crystal (semi-conductor) is Show Answer

Q382) The binary number 10111 is equivalent to the decimal number
Show Answer

Q383) if the forward voltage in a diode is increased, the width of the depletion region
Show Answer

Q384) The n-type semiconductors are obtained, when germanium is doped with
Show Answer

Q385) In forward bias, the width of potential barrier in a P-N junction diode
Show Answer

Q386) In a P-N junction diode if
P region is heavily doped than n region then the depletion layer is Show Answer

Q387) 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

Q388) Electric conduction in semi-conductor takes place due to
Show Answer

Q389) For germanium crystal, the forbidden energy gap in joules is
Show Answer

Q390) In an insulator, the forbidden energy gap between the valance band and conduction band is of the order of Show Answer

Q391) 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

Q392) In P-N junction, avalanche current flows in circuit when biasing is
Show Answer

Q393) In a P-type semi-conductor, germanium is dopped with Show Answer

Q394) The gate for which output is high, if at least one input is low?
Show Answer

Q395) The phase
difference between input and output voltages of a CE circuit is Show Answer

Q396) To a germanium crystal equal number of aluminium and indium atoms are added. Then
Show Answer

Q397) 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

Q398) While using triode as
an amplifier, we avoid making the grid positive because Show Answer

Q399) Why do we prefer indirectly heated cathode to the directly heated cathode? Show Answer

Q400) Which of the following is not a process involved in fabrication of IC
Show Answer

Q401) p-type semiconductor are
Show Answer

Q402) The temperature of germanium is decreased from room temperature to 100 K, the resistance of germanium Show Answer

Q403) An n-type semiconductor is Show Answer

Q404) Biaxial crystal among the following is
Show Answer

Q405) 14× 10¹⁵electrons reach the anode per second. If the power consumed is 448milli watts then the plate
(anode) voltage is
Show Answer

Q406) The ripple factor in a half wave rectifier is
Show Answer

Q407) The reverse saturation of p-n diode
Show Answer

Q408) The phase difference between input and output voltages of a CE circuit is
Show Answer

Q409) Diode is not considered as linear device because Show Answer

Q410) While using triode as an amplifier, we avoid making the grid positive because,
Show Answer

Q411) Least doped region in a transistor Show Answer

Q412) The main cause of zener breakdown is Show Answer

Q413) 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

Q414) Why is there sudden increase in current in zener diode? Show Answer

Q415) 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

Q416) Which of the following materials in non crystalline
Show Answer

Q417) The addition of antimony atoms to a sample of intrinsic germanium transforms it to a material which is
Show Answer

Q418) 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

Q419) The voltage gain of an amplifier with 9% negative feedback is 10. The voltage gain without feedback will be
Show Answer

Q420) The charge on a hole is equal to the charge of Show Answer

Q421) 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

Q422) Regarding a semiconductor which one of the following is wrong Show Answer

Q423) Bonds in semiconductor are Show Answer

Q424) The temperature coefficient of a zener mechanism is Show Answer

Q425) 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

Q426) Which of the following is not equal to 1 in Boolean algebra? Show Answer

Q427) The temperature coefficient of resistance of a conductor is Show Answer

Q428) Which one of the following is the weakest kind of bonding in solids Show Answer

Q429) Donor type impurity is found in Show Answer

Q430) The Binary Coded Decimal (BCD) equivalent of 429 is Show Answer

Q431) In a transistor in common-emitter configuration, the ratio of power gain to voltage gain is Show Answer

Q432) In breakdown region, a zener diode behaves as a Show Answer

Q433) 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

Q434) Avalanche breakdown is due to Show Answer

Q435) An oscillator in nothing but an amplifier with Show Answer

Q436) In order to rectify an alternating current one uses a Show Answer

Q437) Metallic solids are always opaque because Show Answer

Q438) The coordination number of simple cubic crystal is Show Answer

Q439) Energy bands in solids are a consequence of Show Answer

Q440) Which of the following materials is the best conductor of electricity Show Answer

Q441) Which one is in forward bias Show Answer

Q442) Which of the energy band diagrams shown in the figure corresponds to that of a semiconductor? Show Answer

Q443) The probability of electrons to be found in the conduction band of an intrinsic semiconductor at a finite
temperature Show Answer

Q444) In a properly biased transistor Show Answer

Q445) Which represents NAND gate Show Answer

Q446) The resistivity of a semiconductor at room temperature is in between Show Answer

Q447) 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

Q448) 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

Q449) Identify the incorrect statement regarding a superconducting wire Show Answer

Q450) 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

Q451) To write the decimal number 37 in binary, how many binary digits are required Show Answer

Q452) For a cubic crystal structure which one of the following relations indicating the cell characteristic is
correct? Show Answer

Q453) Zener diode is used as Show Answer

Q454) 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

Q455) 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

Q456) When germanium is doped with phosphorus, the doped material has Show Answer

Q457) Which of these is unipolar transistor Show Answer

Q458) The resistivity (p) of semiconductor varies with temperature. Which of the following curve represent the correct behaviour? Show Answer

Q459) Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R
Assertion A Diffusion current in a p-n junction is greater than the drift current in magnitude if the junction is forward biased.
Reason (R) Diffusion current in a p-n junction is from the n-side to the p-side, if the junction is forward biased.
In the light of the above statements, choose the most appropriate answer from the options given below: Show Answer

Q460) Given below are two statements:
One is labelled as Assertion A and the other is labelled as Reason R.
Assertion (A) Photodiodes are preferably operated in reverse bias condition for light intensity measurement.
Reason (R) The current in the forward bias is more than the current in the reverse bias for a p-n junction diode.
In the light of the above statements, choose the correct answer from the options given below: Show Answer

Q461) Statement I When a Si sample is doped with Boron, it becomes p-type and when doped by Arsenic it becomes n-type semiconductor such that p-type has excess holes and n-type has excess electrons.
Statement II When such p-type and n-type semiconductor are fused to make a junction, a current will automatically flow which can be detected with an externally connected ammeter.
In the light of above statement, choose the most appropriate answer from the options given below. Show Answer

Q462) Which one of the following statement is not correct in the case of light emitted diodes?
A. It is a heavily doped p-n junction
B. It emits light only when it is forward biased.
C. It emits light only when it reverse biased.
D. The energy of the light emitted is equal to or slightly less than the energy gap of the semiconductor used.
Choose the correct answer from the options given below Show Answer

Q463) Choose the correct statement about zener diode. Show Answer

Q464) The photodiode is used to detect the optical signals. These diodes are preferably operated in reverse biased mode because Show Answer

Q465) For using a multimeter to identify diode from electrical components, choose the correct statement out of the following about the diode Show Answer

Q466) Identify the solar cell characteristics from the following options. Show Answer

Q467) Statement I To get a steady DC output from the pulsating voltage received from a full wave rectifier we can connect a capacitor across the output parallel to the load RL.
Statement II To get a steady DC output from the pulsating voltage received from a full wave rectifier we can connect an inductor in series with RL.
In the light of the above statement, choose the most appropriate answer from the options given below. Show Answer

Q468) Statement I By doping silicon semiconductor with pentavalent material, the electrons density increases.
Statement II The n-type semiconductor has net negative charge.
In the light of the above statement, choose the most appropriate answer from the options given below. Show Answer

Q469) For extrinsic semiconductors when doping level is increased, Show Answer

Q470) Zener breakdown occurs in a p-n junction having p and n both Show Answer

Q471) When a diode is forward biased, it has a voltage drop of 0.5 V. The safe limit of current through the diode is 10 mA. If a battery of emf 1.5 V is used in the circuit, the value of minimum resistance to be connected in series with the diode, so that the current does not exceed the safe limit is Show Answer

Q472) With increasing biasing voltage of a photodiode, the photocurrent magnitude Show Answer

Q473) The temperature dependence of resistance of Cu and undoped Si in the temperature range 300-400 K, is best described by Show Answer

Q474) A red LED emits light at 0.1 W uniformly around it. The amplitude of the electric field of the light at a distance of 1m from the diode is Show Answer

Q475) In an unbiased p-n junction, electrons diffuse from n-region to p-region because Show Answer

Q476) The forward biased diode connection is Show Answer

Q477) For LED's to emit light in visible region of electromagnetic light, it should have energy band gap in the range of Show Answer

Q478) Carbon, Silicon and germaium have four valence electrons each. At room temperature, which one of the following statements is most appropriate? Show Answer

Q479) If the ratio of the concentration of electrons to that of holes in a semiconductor is 7/5 and the ratio of currents is 7/4, then what is the ratio of their drift velocities? Show Answer

Q480) In the following, which one of the diodes is reverse biased? Show Answer

Q481) The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than 2480 nm, is incident on it. The band gap in (eV) for the semiconductor is Show Answer

Q482) In a full wave rectifier circuit operating from 50 Hz mains frequently, the fundamental frequency in the ripple would be Show Answer

Q483) A piece of copper and another of germanium are cooled from room temperature to 77K, the resistance of Show Answer

Q484) When p-n junction diode is forward biased, then: Show Answer

Q485) The difference in the variation of the resistance with temperature in a metal and a semiconductor arises essentially due to the difference in the Show Answer

Q486) In the middle of the depletion layer of reverse biased p-n junction, the Show Answer

Q487) The energy band gap is maximum in: Show Answer

Q488) By increasing the temperature, the specific resistance of a conductor and a semiconductor Show Answer

Q489) An absolute zero, Si acts as: Show Answer

Q490) Given below are two statements
Statement I In a typical transistor , all three regions emitter, base and collector have same doping level.
Statement II In a transistor, collector is the thickest and base in the thinnest segment.
In the light of the above statement, choose the most appropriate answer from the options given below. Show Answer

Q491) Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R
Assertion (A) n-p-n transistor permits more current than a p-n-p transistor.
Reason (R) Electrons have greater mobility as a charge carrier.
Choose the correct answer from the options given below: Show Answer

Q492) For a transistor to act as a switch, it must be operated in: Show Answer

Q493) The positive feedback is required by an amplifier to act an oscillator. The feedback here means: Show Answer

Q494) Given below are two statements:
Statement I p-n junction diodes can be used to function as transistor, simply by connecting two diodes, back to back, which acts as the base terminal.
Statement II In the study of transistors, the amplification factor beta indicated ratio of the collector current to the base current.
In the light of the above statements, choose the correct answer from the options given below. Show Answer

Q495) If an emitter current is changed by 4 mA, the collector current changes by 3.5 mA. The value of beta will be: Show Answer

Q496) For the transistor in CE mode to be used as an amplifier, it must be operated in Show Answer

Q497) In a common emitter amplifier circuit using an n-p-n transistor, the phase difference between the input and the output voltages will be Show Answer

Q498) The current gain of a common emitter amplifier is 69. If the emitter current is 7.0 mA, collector current is Show Answer

Q499) In a common base amplifier, the phase difference between the input signal voltage and output voltage is Show Answer

Q500) When n-p-n transistor is used as an amplifier Show Answer

Q501) Which of the following gives a reversible operation? Show Answer

Q502) Which one of the following is the boolean expression for NOR gate? Show Answer

Q503) The output of an OR gate is connected to both the inputs of a NAND gate. The combination will serve as a Show Answer