Explore topic-wise MCQs in Physical Electronics Devices and ICs.

This section includes 521 Mcqs, each offering curated multiple-choice questions to sharpen your Physical Electronics Devices and ICs knowledge and support exam preparation. Choose a topic below to get started.

1.

The transconductance gm of the transistor shown below in figure is 10 mS. The value of the input resistance Rin is

A. 10 0 k
B. 8 3 k
C. 5 0 k
D. 2 5 k
Answer» D. 2 5 k
Discussion
2.

Consider the circuit shown in figure below. If the of the transistor is 30 and ICBO = 20 nA and the input voltage is + 5 V, the transistor would be operating in

A. Saturation region
B. Active region
C. Breakdown region
D. Cut-off region
Answer» C. Breakdown region
Discussion
3.

The common emitter forward current gain of the transistor shown below is F = 100. The transistor is operating in

A. Saturation region
B. Cut-off region
C. Reverse active region
D. Forward active region
Answer» D. Forward active region
Discussion
4.

Which of the following can be determined by using a Hall crystal? 1. Concentration of holes in a p-type semiconductor. 2. Concentration of electrons in an n-type semiconductor. 3. Temperature of a the set-up with any type of semiconductor. 4. Diffusion constant and life-time of minority carriers of any type of semiconductor. Select the correct answer using the code given below:

A. Only 1 and 2
B. 1, 2 and 4
C. Only 3 and 4
D. Only 2 and 4
Answer» B. 1, 2 and 4
Discussion
5.

With this Zener diode in its on state . What is the level of IZ for the maximum load resistance?

A. 0 mA
B. Undefined
C. Equal to I
D. I
Answer» E.
Discussion
6.

In a voltage regulator network with fixed RL and R, what element dictates the minimum level of source voltage?

A. V
B. I
C. I
D. None of these
Answer» B. I
Discussion
7.

In a Hall effect experiment, a p-type semiconductor sample with hole concentration p1 is used. The measured value of the Hall voltage is VH1. If the p-type sample is now replaced by another p-type sample with hole concentration p2 where p2 = 2p1. What is the net Hall voltage VH2?

A. 2V
B. 4V
C. (1/2)V
D. (1/4)V
Answer» D. (1/4)V
Discussion
8.

Photons of energy 1 53 10 19 joule are incident on a photodiode which has a respectivity of 0 65 A/W. If the optical power level is 10 W, what is the photocurrent generated?

A. 64 A
B. 1 5 A
C. 2 1 A
D. 6 5 A
Answer» E.
Discussion
9.

In a Hall effect experiment, a p-type semiconductor sample with hole concentration p1 is used. The measured value of the Hall voltage is VH1. If the p-type sample is now replaced by another p-type sample with hole concentration p2 where p2 = 2p1. What is the net Hall voltage VH2?

A. 2V
B. 4
C. (1/2)V
D. (1/4)V
Answer» E.
Discussion
10.

A heavily doped n-typed semiconductor has the following data: Hole-electron mobility ratio: 0 4 Doping concentration: 4 2 108 atoms/m3 Intrinsic concentration: 1 5 104 atoms/m3 The ratio of conductance of the n-type semiconductor to that of the intrinsic semiconductor of same material and at the same temperature is given by

A. 0 00005
B. 2,000
C. 10,000
D. 20,000
Answer» C. 10,000
Discussion
11.

The resistivities of the two sides of a step graded junction are 5 -cm (p-side) and 2 5 -cm (n-side). The height of potential barrier V0? (Given p = 475 cm2/Vs and n = 1500 cm2/Vs at room temperature of 300k and ni = 1 45 1010 atoms/cm3)

A. 593 4 mV
B. 593 4 mV
C. 5 934 mV
D. 59 34 mV
Answer» C. 5 934 mV
Discussion
12.

Calculate IL and IZ.

A. 2 mA, 0 mA
B. 4 mA, 2 mA
C. 2 mA, 2 mA
D. 2 mA, 4 mA
Answer» E.
Discussion
13.

The junction on a step-graded p-n junction diode is doped with NA corresponding to 1 acceptor atom per 106 Si atoms. The contact potential V0? (Assume NA = ND, ni = 1 45 1010/ cm3 and Si has 5 1028 atoms/m3)

A. 751 8 mV
B. 751 8 10
C. V
D. 75 18 mV
E. 7 518 V
Answer» B. 751 8 10
Discussion
14.

Consider the regulated power supply given below:Here VZ = 9 1 V and VBE = 0 7 V. Value of V0 is equal to

A. 25 3 V
B. 29 4 V
C. 27 8 V
D. 30 5 V
Answer» C. 27 8 V
Discussion
15.

A Zener diode regulator shown in the figure given below is to be designed to meet the following specifications IL = 10 mA, V0 = 10 V, Vin varies from 30 V to 50 V. The zener diode has VZ = 10 V and IZK (knee current) = 1 mA. For satisfactory operation, which one of the following is correct?

A. R 1800
B. 2000 R 2200
C. 3700 R 4000
D. R > 4000
Answer» B. 2000 R 2200
Discussion
16.

The symbol ICBO signifies the current that flows when some dc voltage is applied

A. In the reverse direction to the collector junction with the emitter open-circuited
B. In the forward direction to the collector junction with the emitter open-circuited
C. In the reverse direction to the emitter junction with the collector open-circuited
D. In the forward direction to the emitter junction with the collector open-circuited
Answer» B. In the forward direction to the collector junction with the emitter open-circuited
Discussion
17.

For the zener diode shown in the figure, the zener voltage at knee is 7V, the knee current is negligible and the zener dynamic resistance is 10 . If the input voltage (V1) range is from 10 to 16V, the output voltage (V0)

A. 7 to 7.29 V
B. 7.14 to 7.29 V
C. 7.14 to 7.43 V
D. 7.29 to 7.43 V
Answer» D. 7.29 to 7.43 V
Discussion
18.

Consider the transistor circuit given below. It is desired to have V0 = Vin. What should be the value of R to achieve the condition. Assume VBE = 0 7 V, VCE(sat) = 0 2V and I = 8 6 mA

A. 1 k
B. 500
C. 2 k
D. 3 k
Answer» C. 2 k
Discussion
19.

The current ICBO

A. Is generally greater in silicon than in germanium transistors
B. Depends largely on the emitter-base junction bias
C. Depends largely on the emitter doping
D. Increases with an increase in temperature
Answer» E.
Discussion
20.

Consider the following statements associated with bipolar junction transistor and junction gate FET 1. The former has higher input impedance than the latter. 2. The former has higher frequency capability than the latter.3. The latter has lower noise figure than the former.4. The latter has higher power rating than the former. Of these statements

A. 1 and 2 are correct
B. 2 and 3 are correct
C. 3 and 4 are correct
D. 1 and 4 are correct
Answer» C. 3 and 4 are correct
Discussion
21.

For the Zener diode shown in the figure, the Zener voltage at knee is 7 V, the knee current is negligible and the Zener dynamic resistance is 10 . If the input voltage (Vi) range is from 10 to 16 V, the output voltage (V0) ranges from

A. 7 00 to 7 29 V
B. 7 14 to 7 29 V
C. 7 14 to 7 43 V
D. 7 29 to 7 43 V
Answer» D. 7 29 to 7 43 V
Discussion
22.

The specification for a silicon transistor are: ICQ = 300 mA and fT = 350 MHz, hfe = 150, Cob = 4 pF. The values of rb e and gm of the transistor will be

A. 92 ohms, 75 mhos
B. 40 ohms, 118 mhos
C. 12 5 ohms, 12 mhos
D. 112 ohms, 10 2 mhos
Answer» D. 112 ohms, 10 2 mhos
Discussion
23.

In figure, all transistors are identical and have a high value of beta ( ). The voltage VDC equal to

A. 10 V
B. 0 V
C. 15 V
D. 5 V
Answer» E.
Discussion
24.

In the circuit shown below V1 = 2 7 V, VBE = 0 7 V and >> 1. The gm of the transistor is

A. 200 m mho
B. 400 m mho
C. 200 ohms
D. 400 ohms
Answer» C. 200 ohms
Discussion
25.

In the following limiter circuit, an input voltage Vi = 10 sin 100 t is applied. Assume that the diode drop is 0 7 V when it is forward biased. The Zener breakdown voltage is 6 8 V. The maximum and minimum values of the output voltage respectively are

A. 6 1 V, 0 7 V
B. 0 7 V, 7 5 V
C. 7 5 V, 0 7 V
D. 7 5 V, 7 5 V
Answer» D. 7 5 V, 7 5 V
Discussion
26.

The current in the diode D1 of question no. 18 if V = 110 V is

A. 0 mA
B. 1 mA
C. 2 mA
D. 1.5 mA
Answer» D. 1.5 mA
Discussion
27.

In figure both transistors are identical and have a high value of beta. Take the do base emitter voltage drop as 0.7 volt and kT/q = 25 mV. The small signal low frequency voltage gain (V0 / Vi) is equal to

A. 0
B.
C. 1.2
D. 1.2
Answer» E.
Discussion
28.

The barrier capacitance CT

A. Increases with the width of the space charge layer
B. Increases with increasing reverse voltage
C. Is due to the immobile charges at the junction varying with the applied voltage
D. Can be defined as Q/V
Answer» D. Can be defined as Q/V
Discussion
29.

The two transistors in figure are identical. If = 25, the current Ic2 is

A. 28 A
B. 23 2 A
C. 26 A
D. 24 A
Answer» C. 26 A
Discussion
30.

The gm of the MOS transistor is 4 mA/V and the common base current gain of the bipolar transistor is 0.99. The transconductance of the composite transistor as shown in the figure below will be

A. 39.6 mA/V
B. 3.96 mA/V
C. 1.98 mA/V
D. 0.99 mA/V
Answer» C. 1.98 mA/V
Discussion
31.

Consider the following semiconductor diodes 1. Germanium diode 2. Silicon diode 3. Tunnel diode 4. Schottky diode The correct increasing order of forward voltage drop of diodes is

A. 1, 2, 3, 4
B. 3, 4, 1, 2
C. 3, 1, 4, 2
D. 1, 3, 2, 4
Answer» D. 1, 3, 2, 4
Discussion
32.

The p-n-p transistor circuit as shown in the above figure is in saturation. Given that VBE = 0.7 V and VCE (sat) = 0.3 V and min. = 20, the value of IC will be

A. 4.7 mA
B. 5.3 mA
C. 8.6 mA
D. 10 mA
Answer» B. 5.3 mA
Discussion
33.

The saturation currents of the two diodes are 1 and 2mA. The breakdown voltages of the diodes are the same and are equal to 100V. The current in the diode D1 if V=90 V is

A. 0 mA
B. 1 mA
C. 2 mA
D. 3 mA
Answer» C. 2 mA
Discussion
34.

Find the correct match between and Group 2 Group 1 Group 2 E. Varactor diode 1.Voltage reference F. PIN diode2. High-frequency switch G. Zener diode 3. Tuned circuits H. Schottky diode 4.Current controlled attenuator

A. E-4, F-2, G-1, H-3
B. E-2, F-4, G-1, H-3
C. E-3, F-4, G-1, H-2
D. E-1, F-3, G-2, H-4
Answer» D. E-1, F-3, G-2, H-4
Discussion
35.

Match List-I (Devices) with List-II (Characteristic) and select the correct answer using the code given below the lists: List-I (a) BJT (b) MOSFET (c) Tunnel diode (d) Zener diode List-II 1. Voltage controlled negative resistance 2. High current gain 3. Voltage regulation 4. High input impedance Codes:

A. 1423
B. 2413
C. 2314
D. 1324
Answer» D. 1324
Discussion
36.

Group I lists four types of p-n junction diodes. Match each device in Group 1 with one of the options in Group 2 to indicate the bias condition of that device in its normal mode of operation.Group 1 Group 2 P. Zener Diode 1.Forward bias Q. Solar cell2. Reverse bias R. LASER diode S. Avalanche Photodiode

A. P-1, Q-2, R-1, S-2
B. P-2, Q-1, R-1, S-2
C. P-2, Q-2, R-2, S-1
D. P-2, Q-1, R-2, S-2
Answer» C. P-2, Q-2, R-2, S-1
Discussion
37.

The cut-in voltage Vr is

A. The same as the barrier potential
B. The same for germanium and silicon
C. The forward voltage below which the current is very small
D. In the region of reverse bias
Answer» D. In the region of reverse bias
Discussion
38.

In the figure shown below, D1 has reverse saturation current of 20 mA and reverse breakdown voltage of 100V, corresponding values for D2 are 50 mA and 50V. The current in the circuit is the circuit is

A. 20 mA, A to B
B. 20 mA, B to A
C. 50 mA, A to B
D. 50 mA, B to A
Answer» D. 50 mA, B to A
Discussion
39.

VP is the pinch-off voltage for VGS = 0 in an FET. When the gate is reverse biased by VG S the pinch-off voltage

A. Will be less than V
B. Will be more than V
C. Will be the same as V
D. Does not depend on V
Answer» B. Will be more than V
Discussion
40.

IC the dc collector current of a BJT = 2 mA at room temperature where kT/q = 25 m volts. Given hfe = 100, the value of hie is given by

A. 125 ohm
B. 25 ohm
C. 1250 ohm
D. 2500 ohm
Answer» D. 2500 ohm
Discussion
41.

Given that CD at forward current of 1 mA is 0.8 F, its value for a current of 4 mA is

A. 0.8 F
B. 0.2 F
C. 1.6 F
D. 3.2 F
Answer» E.
Discussion
42.

Group 1 lists four different semiconductor devices. Match each device in Group 1 with its characteristic property in Group 2.Group 1 Group 2 P. BJP 1.Population inversion Q. MOS capacitor2. Pinch-off voltage R. LASER diode 3. Early effectS. JFET 4. Flat-band voltage

A. P-3, Q-1, R-4, S-2
B. P-1, Q-4, R-3, S-2
C. P-3, Q-4, R-1, S-2
D. P-3, Q-2, R-1, S-4
Answer» D. P-3, Q-2, R-1, S-4
Discussion
43.

Compared to the junction transistor, FET 1. Has a large gain bandwidth product 2. Is less noisy 3. Has less input resistance 4. Has only majority carriers flow

A. 1 and 3
B. 1 and 2
C. 2 and 4
D. 3 and 4
Answer» D. 3 and 4
Discussion
44.

The fT of a BJT is related to its gm, C and C as

A. f
B. = (C
C. + C
D. ) g
Answer» D. ) g
Discussion
45.

Match List-I (Diode) with List-II (Applications) and select the correct answer using the code given below the lists List-I (a) Varactor diode (b) Tunnel diode (c) Photodiode (d) Zener diode List-II 1. To change auxillary storage batteries 2. Best choice for silicon ICs 3. Suitable for ICs of III-V 4. High frequency switching circuit Codes:

A. 2143
B. 3142
C. 3412
D. 2413
Answer» E.
Discussion
46.

In regard semiconductor photodiodes the following statements are mode 1. In a typical volt ampere characteristic for a given illumination, the reverse current is almost constant for increasing reverse voltage. 2. Due to creation of electron hole pairs by incident photons, the essential concentration of majority carriers is much greater than the percentage increase in minority carriers. 3. The radiation can be considered as a minority carrier injector. 4. The photo-current is due to drifting of injected carriers. Of the four statements, the correct statements are

A. 2, 4
B. 1, 2
C. 2, 3
D. 1, 3
Answer» E.
Discussion
47.

The JFET in the circuit shown in figure has an IDSS = 10 mA and VP = 5 V. The value of the resistance RS for a drain current IDS = 6.4 mA is (select the nearest value)

A. 150 ohm
B. 470 ohm
C. 560 ohm
D. 1 kilo ohm
Answer» B. 470 ohm
Discussion
48.

In regard to the reverse biased pn junction photodiode the following statements are made 1. The photon current and the saturation current are in the same direction. 2. While the photon current is essentially due to minority carriers, the saturation current is due to majority carrier flow. 3. The number of electron hole pairs due to illumination is proportional to the number of incident photons. 4. The effect of illumination can be considered as a majority carrier injection. Of the four statements, the true statements are

A. All four
B. (1) and (2)
C. (2) and (4)
D. (1) and (3)
Answer» E.
Discussion
49.

Match List-I with List-II and select the correct answer using the code given below the lists List-I (a) Drift current (b) Einstein s equation (c) Diffusion current(d) Continuity equation List-II 1. Law of conservation of charge 2. Electric field 3. Thermal voltage 4. Concentration gradient Codes:

A. 2143
B. 4321
C. 4123
D. 2341
Answer» C. 4123
Discussion
50.

A Darlington stage is shown in figure. If the transconductance of Q1 is gm 1 and Q2 is gm 2, then the overall transconductance, gm = Icis given by Vbe

A. g
B. 0 5 g
C. g
D. 0 5 g
Answer» E.
Discussion