Resistance (R)

It is the opposition to the flow of electricity. Every material offers some degree of opposition to the flow of electricity. Conductors tend to have a lower resistance whiles non-conductors (insulators) have high resistance.

Resistance in a conductor causes heat to produce when current flows through.

Resistance is measured using an instrument called Ohmmeter. Its unit of measurement is Ohms (Ω). There are devices designed to offer a particular measure of resistance. These devices are known as resistors.

A resistor therefore helps in controlling the amount of electricity flowing in a circuit. An adjustable resistor which can be used in varying the degree of resistance is called a rheostat. It is also sometimes called a variable resistor.

The relationship of Electric current, potential difference and Resistance: it has been observed from electrical investigations that voltage increases as the current increases.

Voltage is therefore proportional to the current; V α I.

It can be concluded that V=IR, since resistance (R) is constant. This relation is what is known as Ohm’s law.