Test: Electronic Devices - 1 - CUET Humanities MCQ

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term "laser" originated as an acronym for "light amplification by stimulated emission of radiation".
Laser action involves all the given phenomena:
(i) Amplification of particular frequency
(ii) Population inversion
(iii) Stimulated emission

The energy gap between a valence band and a conduction band of a semiconductor is between 0.7 eV to 1.3 eV.

Semiconductors are the material whose conductivity lies in between that of the insulators and the conductors. At 0 K, the semiconductors are the insulators. As the temperature increases, the conductivity increases, or we say, the resistivity decreases.

In an n-type semiconductor excess electrons from donor atom reside in donor levels within the upper half of the band gap or just below the conduction band. As such it would take less energy to excite a donor electron into the conduction band than a valence band electron. While in p-type donor level lies closely above the top of the valence band.

Forward current ratio

Hence the correct choice is (1).

NOT Gate:

When both the inputs are short joined, the NAND gate becomes a NOT gate.
As we have the truth table of the NAND gate:
A B Y
0 0 1
0 1 0 This condition is eliminated during joining of both the inputs.
1 0 0 This condition is eliminated during joining of both the inputs.
1 1 0
Hence, the NAND gate behaves as a NOT gate.

With the increase in forward bias, the barrier potential decreases, because of which the current increases. Hence, the width of the depletion region decreases.

The energy of a photon is given by:

The given truth table is for NOR gate. This means that the output will be 1 when all the inputs are less than 1.
The output will be zero, when any one of the inputs is greater than zero.
Y = 
Y = 1, when A, B and C all are 0.
Y = 0, when A, B and C or any of these is 1.

The oscillator and the amplifier work in the same way, but the amplifier requires input where the oscillator does not require any input. When the amplifier connects with positive feedback, it acts as the oscillator. The feedback employed here is positive feedback; this means some amount of the output voltage is given to the input. Hence, the circuit continues its process without any input to the oscillator. The positive feedback is also known as regenerative feedback because the system sustains or regenerates itself without any input source. Hence, the oscillator is nothing but an amplifier with the positive feedback.