Chapter 14: Semiconductor Electronics: Materials, Devices and Simple Circuits

The conductivity of a semiconductor increases with increase in temperature because

(a) number density of free current carriers increases

(b) relaxation time increases

(c) both number density of carriers and relaxation time increase

(d) number density of current carriers increases, relaxation time decreases but the effect of a decrease in relaxation time is much less than the increase in number density

In the figure, Vo is the potential barrier across a p-n junction, when no battery is connected across the junction

(a) 1 and 3 both correspond to forward bias of junction

(b) 3 corresponds to forward bias of junction and 1 corresponds to reverse bias of junction

(c) 1 corresponds to forward bias and 3 corresponds to reverse bias of junction

(d) 3 and 1 both correspond to reverse bias of junction

In the figure, assuming the diodes to be ideal,

(a) D1 is forward biased and D2 is reverse biased and hence current flows from A to B

(b) D2 is forward biased and D1 is reverse biased and hence no current flows from B to A and vice versa

(c) D1 and D2 are both forward biased and hence current flows from A to B

(d) D1 and D2 are both reverse biased and hence no current flows from A to B and vice versa

A 220 V A.C. supply is connected between points A and B in the figure. What will be the potential difference V across the capacitor?

(a) 220V

(b) 110V

(c) 0V

(d) 220 √2 V

Hole is

(a) an anti-particle of the electron

(b) a vacancy created when an electron leaves a covalent bond

(c) absence of free electrons

(d) an artificially created particle

The output of the given circuit in the figure

(a) would be zero at all times

(b) would be like a half-wave rectifier with positive cycles in output

(c) would be like a half-wave rectifier with negative cycles in output

(d) would be like that of a full-wave rectifier

In the circuit shown in the figure, if the diode forward voltage drop is 0.3 V, the voltage difference between A and B is

(a) 1.3 V

(b) 2.3 V

(c) 0

(d) 0.5 V

Truth table for the given circuit in the figure is

(a)

(b)

(c)

(d)

When an electric field is applied across a semiconductor

(a) electrons move from lower energy level to higher energy level in the conduction band

(b) electrons move from higher energy level to lower energy level in the conduction band

(c) holes in the valence band move from higher energy level to lower energy level

(d) holes in the valence band move from lower energy level to higher energy level

Consider an NPN transistor with its base-emitter junction forward biased and collector-base junction reverse biased. Which of the following statements are true?