Page 1023 - Basic Electrical Engineering

d. When an electron breaks a covalent bond and becomes free, a vacancy called hole is
created.

6. Which of the following statements is not true?

a. An n-type material is formed by adding a small amount of pentavalent impurity to
the pure silicon
b. Examples of pentavalent materials are antimony, arsenic, and phosphorous
c. An n-type material, inspite of the presence of a large number of free electrons is still
electrically neutral
d. In an n-type material holes are the majority carriers and electrons are the minority
carriers.

7. The width of the depletion layer of a p–n junction will increase when

a. the p–n junction is forward biased
b. the p–n junction is reverse biased
c. the p–n junction is forward biased with a voltage which is higher than the normal
rating
d. the p–n junction is kept unbiased for a long time.

8. In the reverse-biased state of a diode current flowing, which is called reverse saturation
current is due to

a. majority carriers
b. minority carriers
c. increase in reverse voltage applied externally
d. both majority and minority carriers.

9. Silicon diode is more popular than germanium diode because

a. reverse saturation current of silicon is higher than that of germanium
b. reverse saturation current of silicon is much lower than that of germanium
c. temperature effect on reverse saturation current of silicon diode is very high
d. break down voltage of germanium is higher than that of silicon.

10. Which of the following statements is not true for a zener diode?

a. A forward-biased zener diode behaves identical to a forward-biased diode
b. Zener diode under the reverse-biased condition is used as a voltage regulator
c. Zener diode under the forward-biased condition is used as a voltage regulator
d. The operation of a reverse-biased zener diode is different than that of a reverse-
biased diode.

11. Which of the following statements is not true about the rectified sinusoidal wave?

a. The ripple factor of a full-wave rectifier is 0.48
b. The ripple factor of a half-wave rectifier is 1.21