p-n JUNCTION

Question 1

1. Define an idea diode.

Answer 1

A theoretical diode that acts as a perfect conductor when forward biased (allowing current to flow freely in one direction) and as a perfect insulator when reverse biased (completely blocking current), essentially exhibiting zero resistance in the forward direction and infinite resistance in the reverse direction.

Question 2

2. Mention the 4 types of diode.

Answer 2

1.Rectifier
2.Demodulator/detector
3.OR-gate
4.AND-gate

Question 3

3. Define knee voltage/ potential barrier/ threshold voltage

Answer 3

A diode starts its conduction only when applying a particular forward voltage. This is called potential barrier or knee voltage or threshold voltage.

Question 4

4. What are the values of knee voltage in Si and Ge diodes?

Answer 4

0.6 and 0.3 V respectively

Question 5

5. Diode is ohmic or non ohmic?

Answer 5

Non ohmic

Question 6

6. What are static resistance and dynamic resistance in diode?

Answer 6

Resistance from a specific value in the
V – I tabular column is static and resistance from V – I graph is dynamic resistance.

Question 7

7. Characteristic features of LED, photodiode, solar cell, zener diode

Answer 7

LED emits light and operates in the forward bias mode.

Photodiodes and solar cells operate in reverse bias.

Zener diode is a special voltage regulator diode that is capable of operating in both forward and reverse bias.

Question 8

8. Forward and reverse biasing of diode – shape of Graphs

Answer 8

characteristic curve

Question 9

9. Mention the properties of semi conductors:

Answer 9

(i) They have negative temperature coefficient of
resistance (ii) The forbidden energy gap/ band gap is less than 3eV (iii) Charge carriers in semi
conductors are both holes and electrons (iv) Their conductivity can be increased by temperature
and doping