# MCQs For NCERT Class 12 Physics Chapter 14 Semiconductor Electronics Materials Devices and Simple Circuits

Please refer to the MCQ Questions for Class 12 Physics Chapter 14 Semiconductor Electronics Materials Devices and Simple Circuits with Answers. The following Semiconductor Electronics Materials Devices and Simple Circuits Class 12 Physics MCQ Questions have been designed based on the latest syllabus and examination pattern for Class 12. Our experts have designed MCQ Questions for Class 12 Physics with Answers for all chapters in your NCERT Class 12 Physics book.

## Semiconductor Electronics Materials Devices and Simple Circuits Class 12 MCQ Questions with Answers

See below Semiconductor Electronics Materials Devices and Simple Circuits Class 12 Physics MCQ Questions, solve the questions and compare your answers with the solutions provided below.

Question. In a semiconductor diode, the barrier potential offers opposition to
(a) holes in P-region only
(b) free electrons in N-region only
(c) majority carriers in both regions
(d) majority as well as minority carriers in both regions

C

Question. In Boolean algebra, Y = A + B implies that
(a) output Y exists when both inputs A and B exist
(b) output Y exists when either input A exists or input B exists or both inputs A and B exist
(c) output Y exists when either input A exists or input B exists but not when both inputs A and B exist
(d) output Y exists when both inputs A and B exists but not when either input A or B exist

B

Question. In the half wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be
(a) 25 Hz
(b) 50 Hz
(c) 70.7 Hz
(d) 100 Hz

B

Question. In a full wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be
(a) 25 Hz
(b) 50 Hz
(c) 70.7 Hz
(d) 100 Hz

D

Question. Two ideal diodes are connected to a battery as shown in the circuit. The current supplied by the battery is

(a) 0.75 A
(b) zero
(c) 0.25 A
(d) 0.5 A

D

Question. In a P -N junction
(a) the potential of P & N sides becomes higher alternately
(b) the P side is at higher electrical potential than N side.
(c) the N side is at higher electric potential than P side.
(d) both P & N sides are at same potential.

B

Question. In a CE transistor amplifier, the audio signal voltage across the collector resistance of 2kW is 2V. If the base resistance is 1kW and the current amplification of the transistor is 100, the input signal voltage is
(a) 0.1 V
(b) 1.0 V
(c) 1 mV
(d) 10 mV

D

Question. In a p-n junction having depletion layer of thickness 10–6 m the potential across it is 0.1 V. The electric field is
(a) 107 V/m
(b) 10–6 V/m
(c) 105 V/m
(d) 10–5 V/m

C

Question. The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in the
(a) crystal structure
(b) variation of the number of charge carriers with temperature
(c) type of bonding
(d) variation of scattering mechanism with temperature

B

Question. Transfer characteristics [output voltage (V0) vs input voltage (V1)] for a base biased transistor in CE configuration is as shown in the figure. For using transistor as a switch, it is used

(a) in region (III)
(b) both in region (I) and (III)
(c) in region (II)
(d) in region (I)

B

Question. The figure shows a logic circuit with two inputs A and B and the output C. The voltage wave forms across A, B and C are as given. The logic gate circuit is:

(a) OR gate
(b) NOR gate
(c) AND gate
(d) NAND gate

A

Question. In common emitter amplifier, the current gain is 62. The collector resistance and input resistance are 5 kΩ an 500Ω respectively. If the input voltage is 0.01 V, the output voltage is
(a) 0.62 V
(b) 6.2 V
(c) 62 V
(d) 620 V

B

Question. The time variations of signals are given as in A, B and C. Point out the true statement from the following :

D

Question. In the energy band diagram of a material shown below, the open circles and filled circles denote holes and electrons respectively. The material is

(a) an insulator
(b) a metal
(c) an n-type semiconductor
(d) a p-type semiconductor

D

Question. Distance between body centred atom & a corner atom in sodium(a = 4.225 Å) is
(a) 3.66 Å
(b) 3.17 Å
(c) 2.99 Å
(c) 2.54 Å

A

Question. Which of the following is unipolar transistor?
(a) p – n – p transistor
(b) n – p – n transistor
(c) Field effect transistor
(d) Point contact transistor

C

Question. The intrinsic conductivity of germanium at 27° is 2.13 mho m–1 and mobilities of electrons and holes are 0.38 and 0.18 m2V–1s–1 respectively. The density of charge carriers is
(a) 2.37 × 1019 m–3
(b) 3.28 × 1019 m–3
(c) 7.83 × 1019 m–3
(d) 8.47 × 1019 m–3

A

Question. For a common base amplifier, the values of resistance gain and voltage gain are 3000 and 2800 respectively. The current gain will be
(a) 1.1
(b) 0.98
(c) 0.93
(d) 0.83

C

Question. In a common base amplifier the phase difference between the input signal voltage and the output voltage is
(a) 0
(b) π/4
(c) π/2
(d) π

A

Question. In a reverse biased diode when the applied voltage changes by 1 V, the current is found to change by 0.5 μA. The reverse bias resistance of the diode is
(a) 2 × 105 Ω
(b) 2 × 106 Ω
(c) 200 Ω
(d) 2 Ω.

B

Question. The grid voltage of any triode valve is changed from –1 volt to –3 volt and the mutual conductance is 3 × 10–4 mho. The change in plate circuit current will be
(a) 0.8 mA
(b) 0.6 mA
(c) 0.4 mA
(d) 1 mA

B

Question. If A is the atomic mass number of an element, N is the Avogadro number and a is the lattice parameter, then the density of the element, if it has bcc crystal structure, is

B

Question. Two junction diodes one of Germanium (Ge) and other of silicon (Si) are connected as shown in figure to a battery of emf 12 V and a load resistance 10 k Ω. The germanium diode conducts at 0.3 V and silicon diode at 0.7 V. When a current flows in the circuit, the potential of terminal Y will be

(a) 12 V
(b) 11 V
(c) 11.3 V
(d) 11.7 V

D

Question. The ratio of work function and temperature of two emitters are 1 : 2, then the ratio of current densities obtained by them will be
(a) 4 : 1
(b) 2 : 1
(c) 1 : 2
(d) 1 : 4

D

Question. What is the conductivity of a semiconductor if electron density = 5 × 1012/cm3 and hole density = 8 × 1013/cm3 (μe = 2.3 m2 V–1 s–1, μh = 0.01 m2V–1 s–1)
(a) 5.634
(b) 1.968
(c) 3.421
(d) 8.964.

B

Question. The transfer ratio b of transistor is 50. The input resistance of a transistor when used in C.E. (Common Emitter) configuration is 1kW. The peak value of the collector A.C current for an A.C input voltage of 0.01V peak is
(a) 100 mA
(b) .01 mA
(c) .25 mA
(d) 500 mA

D

Question. Copper has face centered cubic (fcc) lattice with interatomic spacing equal to 2.54 Å. The value of lattice constant for this lattice is
(a) 2.54 Å
(b) 3.59 Å
(c) 1.27 Å
(d) 5.08 Å

B

Question. A semi-conducting 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 reversed, the current drops to almost zero. The device may be
(a) a p-n junction
(b) an intrinsic semi-conductor
(c) a p-type semi-conductor
(d) an n-type semi-conductor

A

Question. The following circut represents

(a) OR gate
(b) XOR gate
(c) AND gate
(d) NAND gate

D

Question. A n-p-n transistor conducts when
(a) both collector and emitter are negative with respect to the base
(b) both collector and emitter are positive with respect to the base
(c) collector is positive and emitter is negative with respect to the base
(d) collector is positive and emitter is at same potential as the base

C

Question. Following diagram performs the logic function of
(a) XOR gate
(b) AND gate
(c) NAND gate
(d) OR gate

B

Question. Reverse bias applied to a junction diode
(a) increases the minority carrier current
(b) lowers the potential barrier
(c) raises the potential barrier
(d) increases the majority carrier current

C

Question. Which one of the following statement is false ?
(a) Pure Si doped with trivalent impurities gives a p-type semiconductor
(b) Majority carriers in a n-type semiconductor are holes (c) Minority carriers in a p-type semiconductor are
electrons
(d) The resistance of intrinsic semiconductor decreases with increase of temperature

B

Question. A common emitter amplifier has a voltage gain of 50, an input impedance of 100Ω and an output impedance of 200Ω. The power gain of the amplifier is
(a) 500
(b) 1000
(c) 1250
(d) 50

C

Question. 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
(a) 0.01 Ω
(b) 0.1 Ω
(c) 10 Ω
(d) 100 Ω

C

Question. 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
(a) 197
(b) 201
(c) 198
(d) 199

D

Question. A half-wave rectifier is being used to rectify an alternating voltage of frequency 50 Hz. The number of pulses of rectified current obtained in one second is
(a) 50
(b) 25
(c) 100
(d) 2000

B

Question. 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
(a) 0.9
(b) 0.7
(c) 0.5
(d) 1.1

C

Question. In a triode, gm = 2 × 10–3 ohm–1 ; μ = 42; resistance of load, R = 50 kilo ohm. The voltage amplification obtained from this triode will be
(a) 30.42
(b) 29.57
(c) 28.18
(d) 27.15

B

Question. A transistor has a base current of 1 mA and emitter current 90 mA. The collector current will be
(a) 90 mA
(b) 1 mA
(c) 89 mA
(d) 91 mA

C

Question. Current gain of a transistor in common base mode is 0.95. Its value in common emitter mode is
(a) 0.95
(b) 1.5
(c) 19
(d) (19)–1

C

Question. If a small amount of antimony is added to germanium crystal
(a) it becomes a p–type semiconductor
(b) the antimony becomes an acceptor atom
(c) there will be more free electrons than holes in the semiconductor
(d) its resistance is increased

C

Question. One serious drawback of semi-conductor devices is
(a) they do not last for long time.
(b) they are costly
(c) they cannot be used with high voltage.
(d) they pollute the environment.

C

Question. Radiowaves of constant amplitude can be generated with
(a) FET
(b) filter
(c) rectifier
(d) oscillator

D

Question. Zener diode is used for
(a) amplification
(b) rectification
(c) stabilisation
(d) all of the above

C

Question. Minority carriers in a p-type semiconductor are
(a) free electrons
(b) holes
(c) neither holes nor free electron
(d) both holes and free electrons.

A

Question. In insulator
(a) valence band is partially filled with electrons
(b) conduction band is partially filled with electrons
(c) conduction band is filled with electrons and valence band is empty
(d) conduction band is empty and valence band is filled with electrons.

D

Question. In forward biasing of the p–n junction
(a) the positive terminal of the battery is connected to p–side and the depletion region becomes thick
(b) the positive terminal of the battery is connected to n–side and the depletion region becomes thin
(c) the positive terminal of the battery is connected to n–side and the depletion region becomes thick
(d) the positive terminal of the battery is connected to p–side and the depletion region becomes thin

D

Question. At absolute zero, Si acts as
(a) non-metal
(b) metal
(c) insulator
(d) none of these