Question 1

The types of carriers in a semiconductor are

Accepted Answer

Holes and electrons.

Question 2

When a voltage is applied to a semiconductor crystal then the free electrons will flow.

Accepted Answer

Since electrons are negatively charged they will flow towards positive terminal.

Question 3

In a bipolar transistor the barrier potential

Accepted Answer

Since there are two p-n junctions, there are two depletion layers and 0.7 V across each layer.

Question 4

The word enhancement mode is associated with

Accepted Answer

MOSFET may be depletion mode or enhancement mode.

Question 5

At very high temperatures the extrinsic semi conductors become intrinsic because

Accepted Answer

Covalent bonds are broken.

Question 6

A potential of 7 V is applied to a silicon diode. A resistance of 1 K ohm is also in series with the diode. The current is

Accepted Answer

Question 7

Secondary emission is always decremental.

Accepted Answer

Sometimes it can be useful also.

Question 8

The number of doped regions in PIN diode is

Accepted Answer

A PIN diode has p and n doped regions separated by intrinsic layer.

Question 9

In an n channel JFET, the gate is

Accepted Answer

Since channel is n type gate must be p type.

Question 10

Recombination produces new electron-hole pairs

Accepted Answer

Due to recombination the number of electron-hole pairs is reduced.

Question 11

A silicon (PN) junction at a temperature of 20°C has a reverse saturation current of 10 pico Ampere. The reverse saturation current at 40°C for the same bias is approximately.

Accepted Answer

By increasing of temperature by 10°C, Io become double so by increasing temperature 20°C, Io become 4 time than initial value... and it is 40 PA.

Question 12

Ferrite have

Accepted Answer

Ferrite is a low density material of composition with Fe2O3 x O, where x is a bivalent metal, such as Cobart, Ni, Mn. These magnetic materials having very low loss of current and used in high frequency circuit.

Question 13

A particular green LED emits light of wavelength 5490, Å, the energy bandgap of the semiconductor material used there is .. h = 6.6 x 10-34 J sec.

Accepted Answer

From Plank equation joule to convert it into electron volt it will be divided by 1.6 x 10-19.

Question 14

The normal operation of JFET is

Accepted Answer

In major portion of drain characteristics ID is constant.

Question 15

In a degenerate n type semiconductor material, the Fermi level,

Accepted Answer

This is due to high level of doping.

Question 16

The power dissipation in a transistor is the product of

Accepted Answer

Maximum power dissipation occurs at collector junction.

Question 17

In an n-p-n transistor biased for operation in forward active region

Accepted Answer

In forward active mode emitter base junction is forward biased and base collector junction is reverse biased.

Question 18

In a zener diode

Accepted Answer

When reverse voltage equals breakdown value it starts conducting and voltage does not increase further.

Question 19

As compared to an ordinary semiconductor diode, a Schottky diode

Accepted Answer

Cut in voltage in Schottky diode is about 0.3 V as compared to 0.7 V in ordinary semiconductor diode.

Question 20

A periodic voltage has following value for equal time intervals changing suddenly from one value to next... 0, 5, 10, 20, 50, 60, 50, 20, 10, 5, 0, -5, -10 etc. Then rms value of the waveform is

Accepted Answer

RMS value = 965 = 31.064 Volt.

Electronic Devices and Circuits Questions