Semiconductor Electronics · Question 78

A p-n photodiode is made of a material with a band gap of 2.0 eV. The minimum frequency of the radiation that can be absorbed by the material is nearly

1. 1 1014 Hz
2. 20 1014 Hz
3. 10 1014 Hz
4. 5 1014 Hz

The voltage gain of an amplifier with 9% negative feedback is 10. The voltage gain without feedback will be

1. 1.25
2. 100
3. 90
4. 10

Which one of the following represents forward bias diode?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

In the following circuit, the output Y for all possible inputs A and B is expressed by the truth table. [figure]

1. [figure]
2. [figure]
3. [figure]
4. [figure]

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

1. an insulator
2. a metal
3. an n-type semiconductor
4. a p-type semiconductor

The following figure shows a logic gate circuit with two inputs A and B and the output C. [figure] The voltage waveforms of A, B and C are as shown below. [figure] The logic circuit gate is

1. OR gate
2. AND gate
3. NAND gate
4. NOR gate

Which one of the following represents forward bias diode ?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

A transistor is operated in common emitter configuration at constant collector voltage VC = 1.5 V such that a change in the base current from 100 to 150 produces a change in the collector current from 5 mA to 10 mA. The current gain is

1. 50
2. 67
3. 75
4. 100

Choose the only false statement from the following.

1. In conductors the valence and conduction bands overlap.
2. Substances with energy gap of the order of 10 eV are insulators.
3. The resistivity of a semiconductor increases with increase in temperature.
4. The conductivity of a semiconductor increases with increase in temperature.

Zener diode is used for

1. amplification
2. rectification
3. stabilisation
4. producing oscillations in an oscillator.