A p-n junction diode conducts significantly only when forward biased, and a silicon diode's barrier potential is about 0.7 V, so this Class 12 sheet opens with the bias direction and the silicon voltage. The answers record holes as the p-side carriers and 0.3 V for germanium.
Key Takeaways
A p-n diode conducts significantly when forward biased (Q1).
A silicon p-n diode has a barrier potential near 0.7 V (Q2).
Q6 records 0.3 V for germanium.
Section A: Multiple Choice Questions (1 Mark Each)
Choose the correct option for each question.
1.A p-n junction diode allows a significant current to flow only when it is
2.The barrier potential of a silicon p-n junction diode is approximately
(a) 0.3 V(b) 0.7 V(c) 1.1 V(d) 2.1 V
3.The majority charge carriers in a p-type semiconductor are
(a) Electrons(b) Holes(c) Ions(d) Neutrons
4.The majority charge carriers in an n-type semiconductor are
(a) Electrons(b) Holes(c) Ions(d) Protons
5.A diode is used as a rectifier because it
(a) Rectifies resistance(b) Conducts in only one direction(c) Amplifies signals(d) Stores charge
6.The barrier potential of a germanium p-n junction diode is approximately
(a) 0.3 V(b) 0.7 V(c) 1.1 V(d) 2.1 V
Section B: Short Answer Type Questions (2 Marks Each)
Show all steps clearly.
7.What are the majority charge carriers in a p-type semiconductor?
8.What is the barrier potential of a silicon diode?
9.In which bias does a p-n junction diode conduct a large current?
10.What is a rectifier?
11.Name the three terminals of a transistor.
12.What is a full-wave rectifier?
13.What is the barrier potential of a germanium diode?
14.What is a p-type semiconductor doped with?
Section C: Numericals & Word Problems (3 Marks Each)
Apply the concepts to solve the problems. Show all working.
15.A p-n junction diode has a forward voltage drop of 0.7 V. It is used in a circuit with a 5 V supply and a 430 Ω resistor. Find the current through the diode.
16.Explain how a diode acts as a half-wave rectifier.
17.A silicon diode has a barrier potential of 0.7 V. What is the minimum supply voltage required to make it conduct significantly?
18.State the difference between a p-type and an n-type semiconductor.
19.In a full-wave rectifier using a centre-tapped transformer, what is the role of the two diodes?
20.Why is the current through a p-n junction diode very small in reverse bias?
Answer Key
1. a) Forward biased
2. b) 0.7 V
3. b) Holes
4. a) Electrons
5. b) Conducts in only one direction
6. a) 0.3 V
7. Refer to solution guide.
8. Refer to solution guide.
9. Refer to solution guide.
10. Refer to solution guide.
11. Refer to solution guide.
12. Refer to solution guide.
13. Refer to solution guide.
14. Refer to solution guide.
15. Refer to solution guide.
16. Refer to solution guide.
17. Refer to solution guide.
18. Refer to solution guide.
19. Refer to solution guide.
20. Refer to solution guide.
End of Worksheet
People Also Ask
When does a p-n junction diode conduct significantly?
When forward biased, option (a) in this worksheet (Q1).
What is the barrier potential of a silicon diode?
About 0.7 V, option (b) in this worksheet (Q2).
What are the majority carriers on the p side?
Holes, option (b) in this worksheet (Q3).
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