Diodes

Question 1

Approximate thickness of depletion layer?

Answer 1

10^-6 m
Or
1 micrometer

Question 2

Potential barrier (Vb) for Germanium diode

Answer 2

0.3V

Question 3

Potential barrier for silicon diode

Answer 3

0.7V

Question 4

Barrier electric field is of the order?

Answer 4

10^5 Vm-1

Question 5

For forward biasing forward current is of the order

Answer 5

mA

Question 6

For reverse biasing the order of reverse current is

Answer 6

MicroAmpere

Question 7

What is the Richardson-Dushman Equation for half wave rectifier?

Answer 7

J= A x t^2 x e^(W/kT)

Where:
W- work function
k- Boltzmann’s constant
A-constant for pure metals= 60 A/cm2

Question 8

Child Langmuir Law

Answer 8

For a space charge limited current :-

L~ (V)^3/2

Question 9

Vrms =?

Answer 9

Vpeak/2

Question 10

Vdc =? (For half wave rectifier)

Answer 10

Vpeak/||

Question 11

Vpeak =?

Answer 11

2xVrms = ||xVdc

Question 12

Vdc for full wave rectifier ?

Answer 12

2xVpeak/||

Question 13

Ripple?

Answer 13

AC components present in rectifier’s outputs

Question 14

Ripple factor (r)?

Answer 14

Measurement of AC components in a rectifier’s output

Question 15

Ripple factor(r) for half wave rectifier

Answer 15

1.21

Question 16

Ripple factor for full wave rectifier

Answer 16

0.48

Question 17

In reverse biased mode how does the LED work

Answer 17

It works like a normal diode

Question 18

LED’s light emitting intensity is

Answer 18

Directly Proportional to forward current

Question 19

Photodiode materials?

Answer 19

Cadmium Sulphide (CdS)
Serilium (Se)
Zinc Sulphide (ZnS)

Question 20

For a photodiode Energy of incident light photon must be

Answer 20

Greater than the forbidden gap energy

Question 21

In Solar cells one of the semiconductors is made extremely small

Answer 21

So that solar radiation falling on it passes to the junction without any absorption

Question 22

Popularly used solar cells?

Answer 22

Nickel-Cadmium             (Ni-Cd)cell
Lead Sulphide(PbS) cell

Question 23

Width of depletion zone is

Answer 23

Dependant of dopant densities

Question 24

On forward biasing a p-n junction

Answer 24

Number of donors in n-side increase

Question 25

On forward biasing the width of depletion layer

Answer 25

Decreases

Question 26

On reverse biasing the width of depletion layer

Answer 26

Increases

Question 27

Photodiode is

Answer 27

Reverse biased and heavily doped

Question 28

LED is

Answer 28

Forward biased

Question 29

Materials used to make LED diodes

Answer 29

GaAs

GaP