Practice Test

Q1) To provide the abundance of holes the impurity added should be : Show Answer

Q2) For forward biasing P-N junction the positive terminal of the battery is connected to : Show Answer

Q3) To produce N-type crystal Ge or Si may be doped with a substance that is : Show Answer

Q4) A p-type semiconductor can be obtained by adding : Show Answer

Q5) Frequency of an oscillator is given by : Show Answer

Q6) In NOT operation if Y is output and A is input, then : Show Answer

Q7) The pure semiconductor has : Show Answer

Q8) The type of bonding in Ge crystal is : Show Answer

Q9) N-type Ge is obtained on doping the Ge crystal with : Show Answer

Q10) 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

Q11) Majority current carries in N-Types are : Show Answer

Q12) The number of valency electrons in a good conductor is generally : Show Answer

Q13) The electrons are forbidden in a brand in a crystal called the : Show Answer

Q14) The behaviour of Ge as a semiconductor is due to the width of : Show Answer

Q15) When we apply reverse bias to a junction diode it : Show Answer

Q16) The depletion layer in the P-N junction is caused by : Show Answer

Q17) Digital circuits can be made to be respective use of Show Answer

Q18) NOR gate is a combination of Show Answer

Q19) The output of a 2 input OR gate is 0 only what its : Show Answer

Q20) A solid having uppermost energy - band partially filled with electrons is called : Show Answer

Q21) In which of the following states of matter the atomic kinetic and potential energies are comparable ? Show Answer

Q22) CuNi exhibits : Show Answer

Q23) Which of the binding is weakest in strength ? Show Answer

Q24) Which of the following is supercooled ? Show Answer

Q25) What helped in the study of the geometry of the internal structured of the crystals ? Show Answer

Q26) The density of a crystalline material is equal to the : Show Answer

Q27) Which one of the following shows correctly the input characteristics of a transistor in common base configuration ? Show Answer

Q28) In a semiconductor crystal, if the current flows due to breakage of crystal bonds, then the semiconductor is called : Show Answer

Q29) When two semiconductors of P and N-type are brought into contact, they form a P-N junction which acts like a : Show Answer

Q30) In the case of forward biasing of P-N junction, which one of the following figures correctly depicts the direction of flow of charge carriers ? Show Answer

Q31) On increasing the reverse bias to a large value in a P-N junction diode current : Show Answer

Q32) When N- type of semiconductor is heated Show Answer

Q33) The depletion layer in the P-N junction region is caused by : Show Answer

Q34) How many NAND gates are used to form AND gate ? Show Answer

Q35) The "FREE ELECTRON " model of metallic solid does not explain : Show Answer

Q36) Which gate is formed by inverting the output of AND gate ? Show Answer

Q37) 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

Q38) Energy bonds in solids are a consequence of : Show Answer

Q39) When aluminium is added as an impurity to silicon, then resulting material is : Show Answer

Q40) In junction diode, the holes are because of : Show Answer

Q41) Which of the following is NOT equal to O in the Boolean algebra ? Show Answer

Q42) In the Boolean algebra which of the following is NOT equal to A ? Show Answer

Q43) The nature of binding for a crystal with alternate and evenly spaced positive and negative ions is : Show Answer

Q44) The energy gap between conduction band and valence band is order of 0.7 eV. It is a : Show Answer

Q45) What account for flow of charge carriers in forward and reserve biasing of silicon p-n diode ? Show Answer

Q46) For a logic 0101 the waveform is : Show Answer

Q47) Which of the following figure represents an ideal diode characteristics ? Show Answer

Q48) The forward biased diode is : Show Answer

Q49) Which of the following when added as an impurity into the silicon, produces n- type semi - conductor : Show Answer

Q50) In a P-N junction : Show Answer

Q51) In Germanium crystal, impurity donor element have valency : Show Answer

Q52) At 0 K temp., a p-type semiconductor : Show Answer

Q53) The potential barrier in the depletion layer is due to : Show Answer

Q54) Barrier potential of a P- N junction diode does not depend on : Show Answer

Q55) Reverse bias applied on a junction diode : Show Answer

Q56) To a germanium sample, traces of gallium and added as an impurity. The resultant sample would behave like : Show Answer

Q57) 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

Q58) Assertion : In a transistor the base is made thin.
Reason : A thin base makes the transistor stable. Show Answer

Q59) Assertion : A transistor amplifier in common emitter configuration has a low input impedance.
Reason : The base to emitter region is forward biased. Show Answer

Q60) If a full wave rectifier circuit is operating 50 Hz mains, the fundamental frequency ripple will be : Show Answer

Q61) Which of the following can be used as a semiconductor ? Show Answer

Q62) The semiconductor at room temperature : Show Answer

Q63) 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

Q64) The output of OR gate is 1 : Show Answer

Q65) Which of the following logic gates is an universal gate ? Show Answer

Q66) Application of a forward bias to a P-N junction : Show Answer

Q67) Zener diode is used for : Show Answer

Q68) When a P-N diode is reverse biased then : Show Answer

Q69) The output of a diode rectifier is : Show Answer

Q70) In intrinsic semiconductor at room temperature, number of electrons and holes are : Show Answer

Q71) A modulator is used for : Show Answer

Q72) The static amplification factor of a triode value depends upon : Show Answer

Q73) What is the minimum number of parameters required to describe a three dimension crystal system : Show Answer

Q74) The energy gab between the valence band and the conduction band for a material is 6 eV. The material is, Show Answer

Q75) 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

Q76) 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

Q77) The impurity atoms with which a pure silicon should be doped to make a p-type semiconductor is : Show Answer

Q78) At room temperature,a p-type semi conductor has : Show Answer

Q79) NAND gate is : Show Answer

Q80) 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

Q81) 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

Q82) Which one of the following statement is FALSE ? Show Answer

Q83) In forward biasing of the p-n junction : Show Answer

Q84) The lattice parameter for a crystalline structure is 3.6 A. Atomic radius in simple cubic crystal is : Show Answer

Q85) Truth table of NOR gate is : Show Answer

Q86) The conductivity of a semiconductor is given by Show Answer

Q87) A hole diffuses from the P-side to the N-side in a P-N junction. This means that : Show Answer

Q88) Which of the following types of binding produces crystals that are transparent to visible light and conduct electricity only at higher temperatures ? Show Answer

Q89) In case of diamond, the forbidden gap is about : Show Answer

Q90) Metallic solids are always opaque because : Show Answer

Q91) Zener diode is used for Show Answer

Q92) When an impurity is doped into an intrinsic semiconductor the conductivity of the semiconductor Show Answer

Q93) Silicon is a semiconductor. If a small amount of As is added to it, then its electrical conductivity Show Answer

Q94) The valency of an impurity element added to germanium crystal in order to convert it into P - type semiconductor is Show Answer

Q95) An intrinsic - semiconductor at absolute zero of temperatures behaves as Show Answer

Q96) To a germanium sample, traces of gallium are added as an impurity. The resultant sample would behave like Show Answer

Q97) If the forward voltage in a diode is increased, the width of the depletion region Show Answer

Q98) The impurity atom that should be added to Germanium to make its n - type is Show Answer

Q99) 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

Q100) Statement 1 : The conductivity of a semiconductor increases with rise of temperature.
Statement 2 : On rising temperature covalent bonds of semiconductor break.
Show Answer

Q101) The dominant contribution to current comes from holes in case of Show Answer

Q102) Diffusion current in a p-n junction is grearer than the drift current in magnitude Show Answer

Q103) For germanium crystal, the forbidden energy gap in joule is Show Answer

Q104) The band gap in germanium and silicon in eV respectively is Show Answer

Q105) 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

Q106) In an n-type semiconductor, donor valence band is Show Answer

Q107) If no external voltage is applied across p-n junction, there would be Show Answer

Q108) When the conductivity of a semiconductor is only due to breaking of covalent bonds, the semiconductor is called Show Answer

Q109) Reverse bias applied to a junction diode Show Answer

Q110) 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

Q111) 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

Q112) 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

Q113) What will be the forward current at a forward voltage of 0.6 V ? Show Answer

Q114) What will be the increase in the current, if the voltage across the diode is increased to 0.7 V ? Show Answer

Q115) What is the dynamic resistance ? Show Answer

Q116) Which of the following is not analogue signal ? Show Answer

Q117) Refer to the circuit shown in figure. What inputs X and Y will produce a high output at R ? Show Answer

Q118) How many NAND gates are required to make an OR gate ? Show Answer

Q119) 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

Q120) Statement 1 : NOT gate is also called invertor circuit.
Statement 2 : NOT gate inverts the input order.
Show Answer

Q121) The circuit above behaves as Show Answer

Q122) If all the NOR gate in the circuits are replaced by NAND gates, the circuit would perform the logic operation of Show Answer

Q123) The output of OR gate is 1 Show Answer

Q124) The boolean expression for NAND gate is Show Answer

Q125) If A = 1 and B = 0, then A.A + B in the boolean expression is equal to Show Answer

Q126) Which of the following is the logic symbol of NAND gate ? Show Answer

Q127) If one terminal of an XOR gate is kept at 1, the output will be zero when the other terminal is at Show Answer

Q128) In boolean algebra, which of the following is not equal to zero Show Answer

Q129) Which of the following is not correct ? Show Answer

Q130) Identify the gate in box II Show Answer

Q131) Identify the gate in box III Show Answer

Q132) An AND gate can be prepared by repetitive use of Show Answer

Q133) The number of NAND gates required to make NOT gate is Show Answer

Q134) 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

Q135) The logic gate circuit is Show Answer

Q136) Which one of the following cirucits would give waveforms as given in the passage above Show Answer

Q137) What is the forbidden energy gap (in joule) for a Germanium crystal? Show Answer

Q138) There is a small energy gap between the conduction and valence bands of Show Answer

Q139) Silicon and copper are cooled from 300 K to 100 K. The specific resistance (resistivity) Show Answer

Q140) The highest energy level which can be occupied by an electron in valence band at OK is known as Show Answer

Q141) At absolute zero Si acts as Show Answer

Q142) 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

Q143) Choose only the wrong statement from the following: Show Answer

Q144) In good conductors the gap between the valence band and the conduction band is Show Answer

Q145) Carbon, silicon and germanium atoms have four valence electrons each. At room temperature, which of the following statements is most appropriate? Show Answer

Q146) What is the name of the level formed due to the impurity atom in the forbidden energy gap near the valence band in a p-type semiconductor? Show Answer

Q147) The impurity atom with which pure silicon should be doped to make a p type semiconductor is Show Answer

Q148) What is the change in resistance and electrical conductivity of a semiconductor, when its temperature is increased? Show Answer

Q149) In a semiconductor, the energy gap between the valence and conduction bands is 1.1 eV. It is expressed in joules as Show Answer

Q150) The mobility of mobile holes is less than that of mobile electrons because Show Answer

Q151) The electrical conductivity of pure silicon can be increased by Show Answer

Q152) Find the 'wrong' statement from the following:
In a semiconductor
Show Answer

Q153) Which is the wrong statement from the following? Show Answer

Q154) Choose the false statement from the following. Show Answer

Q155) Intrinsic semiconductor is electrically neutral. Extrinsic semiconductor having large number of current carriers is Show Answer

Q156) There are two Ge crystals A and B. Few aluminium atoms are added to A while few Indium atoms are added to B. Then Show Answer

Q157) By increasing the temperature, the specific resistance of a conductor and a semiconductor Show Answer

Q158) In semiconductors at a room temperature Show Answer

Q159) A semiconductor has phosphorus as impurity, then it will have Show Answer

Q160) In a p-type semiconductor, germanium is dopped with Show Answer

Q161) In an insulator Show Answer

Q162) Small pieces of Copper and Germanium are cooled from room temperature to 100 K. Then the resistance of Show Answer

Q163) When the electrical conductivity of a semi-conductor is only due to the breaking of its covalent bonds, then the semiconductor is said to be Show Answer

Q164) In case of a semiconductor, which one of the following statements is wrong? Show Answer

Q165) Which one of the following, when added as an impurity to silicon, produces an n-type semiconductor? Show Answer

Q166) The increase in temperature of a semiconductor, will Show Answer

Q167) Which one of the following statements is wrong?
When a potential difference is applied across, the current passing through Show Answer

Q168) 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

Q169) A semiconducting device is connected in series with a battery and a resistance. A current of 10 mA is found to pass through the circuit. If the polarity of the battery is reversed, the current drops to almost zero. The device may be Show Answer

Q170) If the forward bias voltage of a junction diodes is increased from 0.8V to 2V, the current increases by 4 mA. The forward resistance of the diode is Show Answer

Q171) A half wave rectifier is used to rectify an alternating voltage of frequency 60 Hz. The number of pulses of rectified current obtained in one second is Show Answer

Q172) In which one of the following devices the reverse biased characteristics of a p-n junction diode are used? Show Answer

Q173) A junction diode is forward biased. If the forward voltage is increased from 0.4 V to 0.7 V, the forward current changes by 1.5 mA. What is the forward resistance of the junction diode? Show Answer

Q174) The depletion region of a p-n junction is formed Show Answer

Q175) In a halfwave rectifier, the output frequency is 50 Hz if the input frequency is 50 Hz. What is the output frequency of a fullwave rectifier for the same input frequency? Show Answer

Q176) When the resistance between p and n regions is very high then the p-n junction diode acts as Show Answer

Q177) In a p - n junction, electric conduction takes place due to Show Answer

Q178) The current obtained from a filterless rectifier is Show Answer

Q179) In the case of a p-n junction diode, if the reverse bias is very high, there is a sudden large increase in current. In this case the value of reverse bias voltage is known as Show Answer

Q180) What happens to the depletion region of a p-n junction? Show Answer

Q181) When the p-end of the p-n junction is connected to the negative terminal of the battery and the n-end to the positive terminal of the battery, then the p-n junction behaves like Show Answer

Q182) The electrical circuit used to get smooth d.c. output from a half wave rectifier circuit is called Show Answer

Q183) The depletion layer in the p-n junction region is caused by Show Answer

Q184) In an unbiased p - n junction Show Answer

Q185) The barrier potential of a p-n junction diode does not depend upon the Show Answer

Q186) When a p-n junction diode is forward biased, then Show Answer

Q187) If a full wave rectifier circuit is operating from 50 Hz mains, the fundamental frequency in the ripple will be Show Answer

Q188) The barrier potential of a p-n junction depends on the
(i) type of semi conductor material
(ii) amount of doping
(iii) temperature
Which one of the following is correct? Show Answer

Q189) The frequency of a given AC signal is 50 Hz. When it is connected to a half-wave rectifier, the number of output pulses given by the rectifier in 1 s is Show Answer

Q190) A semiconducting device is connected is series with a battery, a resistance and a microammeter. It is found that there is practically no current in the circuit. But if the polarity of the battery is reversed, there is a sudden increase in the current. The device may be Show Answer

Q191) The dominant mechanism for motion of charge carriers in forward and reverse biased silicon p-n junction are Show Answer

Q192) In the middle of the depletion layer of a reverse biased p-n junction, the Show Answer

Q193) In a p-n junction diode not connected to any circuit Show Answer

Q194) The peak voltage in the output of a half-wave diode rectifier fed with a sinusoidal signal without filter is 10 V. What is the d.c. component of the output voltage? Show Answer

Q195) A semiconductor diode (D) and a resistor R are connected in some way and are kept in a closed box, having two external terminals. When a potential difference of 1 V is applied to their combination, the current I = 25 mA. If the potential difference is reversed, the current becomes 50 mA. What are the values of R and the forward resistance of the diode? Show Answer

Q196) What is the value of D.C. voltage in a half wave rectifier in converting A.C. voltage V = 100 sin (314 t) into D.C.? Show Answer

Q197) Which one of the following is the correct statement regarding the depletion region of an unbiased p-n junction? Show Answer

Q198) The colour of light emitted by a LED depends upon Show Answer

Q199) A general purpose diode is more likely to suffer avalanche breakdown rather than zener breakdown because Show Answer

Q200) GaAs is used to prepare Show Answer

Q201) A solar cell works on the principle of Show Answer

Q202) LEDS used for giving infrared radiations are prepared from Show Answer

Q203) In a circuit a diode was used and the output voltage across the diode was always 50 volts, even if the input voltage fluctuated between 110 V to 90 V. The diode used in the circuit was Show Answer

Q204) For emission of light, a light emitting diode (LED) is Show Answer

Q205) For a transistor circuit in common emitter configuration, the voltage gain is 100. If the input voltage is 20 mV, then the output voltage is Show Answer

Q206) A NOR gate is ON only when all its inputs are Show Answer

Q207) If two inputs of a NAND gate are shorted, the resulting gate is Show Answer

Q208) For which logic gate the following statement is true?
The output is low if and only if all the inputs are high. Show Answer

Q209) The truth table of a logic gate is a table Show Answer

Q210) The logic expression y = ABC is read as Show Answer

Q211) A NOR gate gives Show Answer

Q212) For which logic gate the following statement is true?
The output is low, if and only if all inputs are low. Show Answer

Q213) How many NAND gates are required to form an AND gate? Show Answer

Q214) In a chemical process, alarm systems are to be activated whenever either the pressure or the temperature in the reaction chamber exceeds certain limits. This is done by using a logic gate whose inputs will be the voltages corresponding to the high temperature or high pressure in the reaction chamber. Which logic gate should be used to activate the alarms? Show Answer

Q215) In a two input logic gate, when one input is 1 and the other is zero, the output is one. But even if both inputs are zero, the output is one, the logic gate is Show Answer

Q216) Which logic gate produces 'LOW' output when any of the inputs is "HIGH"? Show Answer

Q217) If the output of two NAND gates is given to input of a NAND gate. Then the truth table will be of Show Answer

Q218) When a hole is produced in a p-type semiconductor, there is Show Answer

Q219) The colour of light emitted by an LED depends upon Show Answer

Q220) In a semiconductor, acceptor impurity is Show Answer

Q221) The width of the depletion region of a p-n junction diode is Show Answer

Q222) The schematic symbol of light emitting diode is (LED). Show Answer

Q223) Photodiode is a device Show Answer