Resistor is one of the passive components used in electronic circuits.

It is used to limit the flow of current in a circuit. It’s main aim is to resists the flow of electricity.

Resistance can be compared to friction. As we know, it is impossible to walk without friction. If friction between our feet and earth surface is too less, we will slip and if the earth surface is very rough, friction is high and we have difficulty walking. Likewise, Resistance is an opposing force which is necessary for the functioning of an electric circuit. If the resistance in the circuit is very less, high current will flow which may burn the components in the circuit.

Resistance is measured in unit called ohm.  Ohm is represented by Greek alphabet ‘Ω’.

Higher units of resistance are represented as :

1000 Ω = 1 Kilo ohm (KΩ)

1,000,000 Ω (1000 KΩ) = 1 Mega ohm (MΩ)

1000 MΩ = 1 Giga ohm (GΩ)

Symbol of Resistance is :






Relationship between voltage, current and resistance can be expressed by ohm’s law.  As per ohm’s law,

Voltage = Current * Resistance


Resistance= Voltage/Current


Current = Voltage/ Resistance

We will study more about resistors in next blog.