Semiconductor Electronics: Materials, Devices and Simple Circuits

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


The logic gate is

•  NOR gate

• OR Gate

• AND gate

• AND gate

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

• 6000 A^o

• 4000 nm

• 6000 nm

• 6000 nm

If a diamagnetic substance is brought near the north or the south pole of a bar magnet, it is 

• repelled by both the poles

• repelled by the north pole and attracted by the south pole

• attracted by the north pole and repelled by the south  pole

• attracted by the north pole and repelled by the south  pole

The symbolic representation of four logic gates


The logic symbols for OR, NOT and NAND gates are respectively

• (iii), (iv), (ii)

• (iv), (i), (iii)

• (iv), (ii), (i)

• (iv), (ii), (i)

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

• 75

• 100

• 150

• 150

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

• 10 x 10¹⁴ Hz

• 5 x 10¹⁴ Hz

• 1 x 10¹⁴ Hz

• 1 x 10¹⁴ Hz

The Circuit is equivalent to 

• AND gate

• NAND gate

• NOR gate

• NOR gate

In the following circuit the output Y for all possible input A and B is expressed by the truth table:

• A	B	Y
  0	0	0
  0	1	0
  1	0	0
  1	1	1

• A	B	Y
  0	0	1
  0	1	1
  1	0	1
  1	1	0

• A	B	Y
  0	0	1
  0	1	1
  1	0	1
  1	1	0

• A	B	Y
  0	0	1
  0	1	1
  1	0	1
  1	1	0

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

• p-type semiconductor

• insulator

• metal

• metal

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

• 67

• 75

• 100

• 100