i)

Types of transistors

1. NPN transistor
2. PNP transistor

ii)

Circuit symbols of NPN transistor

Circuit symbols of PNP transistor

i)

A transistor is a three terminal (a base, emitter and collector) semiconductor device.

ii)

Uses of a transistor

1. Used as an amplifier
2. Used as a switch
3. Used as a rectifier
4. Used for tuning in radios
5. Used as a voltage/current regulator

(i)

Light emitting diode (LED) is a device that emits light when an electric current is passed through it.

(ii)

Devices that use LED in their operation

1. Traffic lights
2. Smart phone screens
3. Aviation lights
4. Digital watch

(i)

Active Region

The active region is defined as the region in which the emitter-base junction is forward biased and the collector-base junction is reverse biased.

(ii)

In the active region of a transistor, the transistor behaves as an amplifier

i)

Junctions of a transistor

1. Base-emitter
2. Base-collector

ii)

Symbol for n-p-n transistor