Semiconductor Electronics

A p-n photodiode is fabricated from a semiconductor with a band gap of 2.5 eV. It can detect a signal of wavelength

1. 4000 nm
2. 6000 nm
3. 4000 A
4. 6000 A

The symbolic representation of four logic gates are given below [figure] The logic symbols for OR, NOT and NAND gates are respectively

1. (iv), (i), (iii)
2. (iv), (ii), (i)
3. (i), (iii), (iv)
4. (iii), (iv), (ii)

A transistor is operated in common-emitter configuration at VC = 2 V such that a change in the base current from 100 to 200 produces a change in the collector current from 5 mA to 10 mA. The current gain is

1. 100
2. 150
3. 50
4. 75

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]