8 ELECTRONICS

8.1 Electronic components

• Fixed resistance or resistor:

A fixed resistance or resistor opposes the flow of electric currents. Its value, which we measure in ohms, is indicate by a code of colours and numbers

• Variable resistance or potentiometer

The value of a variable resistance or potentiometer can be adjusted between zero and the maximum value specified by the manufactured.

• Resistance that dependes on a physical factor

The physical factors that affect resistance may be temperature or the amount of ligtht, for example.

Resistance that depends on temperature is called a thermistor.

• Negative temperature coefficient (NTC): The resistance decreases as the temperate rises.
• Positive temperature coefficient (PTC): The resistance increases as the temperaature rises.

LDR: resistance thatvaries according to the amount of ligth received. The resistance decreases as the amount of ligth increases.

• Capacitors

Capacitors are componets that can store an electrical charge. The value of a capacitors indicates the charge in volts that it can store. This is measured in farads (F)

• Diodes

A diode is an electronic component made from semiconductor materials. A diode has two electrodes: an anode (A) and a cathode (K)

A LED only gives off ligth when an electric current flows through it.