Circuit Devices

Special device made from semiconductor material such as silicon.

Used to regulate potential difference in circuits.

Lets current flow freely in one direction but not the other - high resistance in reverse direction.

Very useful in various electronic circuits.

LED emits light when current flows through in forward direction.

LEDs used more and more as lighting as they use smaller current than other forms of lighting.

LEDs indicate presence of current in circuit, often used in appliances to show they are switched on.

Used for numbers on digital clocks, traffic lights and remote controls.

LDRs dependent on intensity of light.

In bright light, resistance falls.

In darkness, resistance increases.

Applications: automatic night lights, outdoor lighting, burglar detectors.

Temperature dependent resistor.

Hot conditions - resistance drops. 

Cold conditions - resistance increases.

Make useful temperature detectors e.g. car engines, electronic thermostats.