Semiconductor Electronics

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

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

For transistor action Which one of the following pairs of statements is correct?

1. D and A
2. A and B
3. B and C
4. C and D

To get an output Y = 1 in given circuit which of the following input will be correct? [figure]

1. A 1, B 0, C 0
2. A 1, B 0, C 1
3. A 1, B 1, C 0
4. A 0, B 1, C 0

Which one of the following statements is false?

1. Pure Si doped with trivalent impurities gives a p-type semiconductor.
2. Majority carriers in a n-type semiconductor are holes.
3. Minority carriers in a p-type semiconductor are electrons.
4. The resistance of intrinsic semiconductor decreases with increase of temperature.

Which one of the following bonds produces a solid that reflects light in the visible region and whose electrical conductivity decreases with temperature and has high melting point?

1. metallic bonding
2. van der Waals' bonding
3. ionic bonding
4. covalent bonding

The device that can act as a complete electronic circuit is

1. junction diode
2. integrated circuit
3. junction transistor
4. zener diode

A common emitter amplifier has a voltage gain of 50, an input impedance of 100 and an output impedance of 200 . The power gain of the amplifier is

1. 500
2. 1000
3. 1250
4. 50

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