Transistors

Question 1

What is a Transistor?

Answer 1

Is an electronic device that is used to control the follow of current in electrical circuits

Question 2

In what two ways can a Transistor be used?

Answer 2

• as switches

- as amplifiers

Question 3

Explain how transistor can be used as a switch?

Answer 3

• The output is either on or off depending on the current which usually comes from a sensor
• transistors used in this way is called NPN transistors

Question 4

Explain how transistor can be used as a amplifier?

Answer 4

• The output current is an enlarged version of the input current
• such transistors are called PNP transistors

Question 5

Can one easily tell the difference between an NPN and a PNP transistor?

Answer 5

No there is no easy way of telling the difference between a NPN and PNP transistor - so take care not to mix up these resistors

Question 6

Which transistors are used in Grade 9?

Answer 6

NPN transistors are used

Question 7

How many legs does a transistor have?

Answer 7

3

Question 8

Give the names and the symbols for the 3 legs of an NPN transistor

Answer 8

• base (b)
• collector (c)
• emitter (e)

**look at figure 11.9 in your book