21. Read the text again and complete the sentences.

1. The P-N-P transistor is … .

2. The geometry of junction transistors differs depending on … .

3. … the transistor may be considered as two diodes.

4. The emitter-base constitutes … .

5. … are the majority current carriers in the emitter-base diode.

6. The emitter-collector circuit is … .

7. Collector current may be controlled readily by … .

8. … may also be made with an N-P-N configuration.

9. Base current will increase or decrease very little when … .

10. Changes in emitter-base bias will result in … .

22. Match the terms in Table A with their definitions in Table B.

Table A

Table B

beam satellite transistor base sensitivity

The ability to react to very small changes in light, heat, movement etc. The lowest part or surface of something [= bottom] A line of light, energy etc that you cannot see. A machine that has been sent into space and goes around the Earth, moon etc, used for radio, television, and other electronic communication. A small piece of electronic equipment in radios, televisions etc that controls the flow of electricity.

Speaking

23. Summarize the text “Junction Transistors” in 150 words.

24. Divide into 2 groups. Group 1 translates Extract a and group 2 – extract b of the text with a dictionary in writing.

Extract A 

The Transistor

Scientific interest in semiconductors led to the development of the transistor. One advantage of the transistor is that it is small and light, permitting miniaturization of electronic equipment. The transistor operates with low voltages and uses little power. It does not require any warm up period and operates as soon as power is applied. A transistor has fewer circuit connections. A disadvantage of transistors is their sensitivity to heat, but an advantage is that they do not generate much heat.

There are many types of transistors. They may be classified according to the basic material from which they are formed. In this category we find germanium and silicon transistors. Most transistors are now made of silicon. Transistors may be classified also according to the process by which they are constructed. Here we find various types of junction transistors and point-contact transistors.

Transistors may also be classified according to the number of elements. Thus there is the triode, or three-element transistor, and the tetrode, or four-element transistor. They may also be classified according to their ability to dissipate power. Here we find a wide range from the low-power (less than 50 mW) to the high-power (2W and higher) type.

Transistors come in different shapes and sizes. There are variations also in the manner of mounting the transistor in the circuit.

Extract B