(c) What is meant by intrinsic conduction? (d) What is meant by doping?
(e) Give one difference between a p-type semiconductor and an n-type semiconductor. (f) What is the net electric charge on a p-type semiconductor? (g) What is a diode?
(h) Give an example of a device that contains a rectifier.
(7) (7) (7) (7) (7) (7)
‘SECTION B’
HALF QUESTION Typical of Question 12 in Leaving Cert. Exam
Q5 Answer both of the following parts (a) and (b). (a) A semiconductor can be doped to form a p–n junction creating a depletion layer at the junction. (i) What is a p–n junction?
(ii) Explain how a depletion layer is formed at the junction.
(iii) Draw a diagram illustrating the difference between a p–n junction connected in forward bias to a d.c. supply and one connected in reverse bias.
(6) (9)
(4)
(iv) The circuit diagram in Fig 19.21 contains two 2 signal lamps,A and B.What is observed when the switch is closed? Explain why.
(9)
A
B Fig 19.21 (b) Name the electrical component represented in Fig 19.22. Fig 19.22
Name a substance that could be used in the production of light-dependent resistors. Describe an experiment to demonstrate the effect of light on an LDR. Give two uses of a light-dependent resistor (LDR).
