Semiconductor physics and diodes. Part – 1

1. The impurity atoms in semiconductors.

A. Injects more charge carriers

B. Increase the kinetic energy of valance electrons

C. Reduces the energy gap

D. All of the above

2. Current flow in a semiconductors depends on the phenomenon of

A. Drift

B. Diffusion

C. Recombination

D. All of these

3. The maximum efficiency of a full wave rectifier is

A. 40.6%

B. 100%

C. 81.2%

D. 85.6%

4. The width of depletion layer of the PN junction

A. Decreases with light doping

B. Increase with heavy doping

C. Is independent of applied voltage

D. Is increase under reverse bias

5. Ripple frequency of the output waveform of a bridge rectifier when fed with a 50 Hz sine wave is

A. 100 Hz

B. 25 Hz

C. 50 Hz

D. none of the above

6. The forward resistance of the diode will be,

A. Small

B. High

C. Zero

D. Infinite

7. An AC voltage can be converted into a uni-directionl voltage by using,

A. Oscillator

B. Rectifier

C. Chopper

D. Amplifier

8. In a semi-conductor diode, the barrier offers opposition to

A. Majority carriers in both regions

B. majority as well as minority carriers in both region

C. free electrons in N- region only

D. holes in P- region only

9. A zener diode, the breakdown is due to zener, has doping

A. Moderate

B. High

C. Low

D. Lowest

10. For insulator the forbidden gap is in order of?

A. 5 ev

B. 1 ev

C. 0.1 ev

D. Zero