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Written Questions: Semiconductors

<^< Multiple Choice Quiz: Semiconductors | Course Index | Assignment: Semiconductors >^>(:nl:)

The section on the right contains a list of written questions. These can be printed out for your own use.

1.
(a) Sketch the simplified construction of a P-N junction diode. Label your drawing clearly.
(b) Explain, briefly, what happens when the device in (a) is (i) forward biased and (ii) reverse biased.Illustrate your answer with relevant diagrams.

2. Sketch a typical set of forward and reverse characteristics for a typical silicon diode. Label your graph with typical values.

3.
(a) Sketch the simplified construction of an NPN bipolar junction transistor. Label your drawing clearly.
(b)Identify the base, emitter and collector connections in (a).
(c) Explain, briefly, what happens when normal bias voltages are applied to the device in (a).

4. With reference to an NPN bipolar junction transistor, explain each of the following terms:
(a) majority carriers
(b) minority carriers
(c) recombination.

5. An NPN transistor operates with I'_E_' = 2 mA and I'_B_' = 1.9 mA. Determine the value of I'_C_' and the common emitter current gain, h'_FE_'.

6. Sketch circuit symbols for each of the following semiconductor devices:
(a) a semiconductor diode
(b) a zener diode
(c) an NPN transistor
(d) a PNP transistor.

7. For a small-signal NPN transistor, sketch:
(a) a typical transfer characteristic (I'_C_' plotted against I'_B_')
(b) a typical output characteristic (I'_C_' plotted against V'_CE_').

8. A DC power supply produces an output of 7.5 V. The output is to be indicated using an LED rated for operation with a forward voltage of 2.2 V and a current of 20 mA. Sketch a circuit showing how the LED should be connected and specify the value of any additional component required.

9. A zener diode rated at 4.7 V is connected in series with a 220 &#937; resistor across the output of a 12 V power supply. Determine the approximate current flowing in the zener diode and the power that will be dissipated in it. (:nl:)(:table style="clear:both":)