Electric Current: Electric current can be defined as the rate of transfer of electric charge across a cross sectional boundary. The current flows opposite to the motion of electrons. It is represented by ‘I’ and its unit is ampere.

I = dq/dt

Where q is the electric charge.

Potential Difference: Potential difference is responsible for the flow of current in a closed circuit. Larger is the potential difference, larger will be the larger will be the current strength and vice versa. It can be defined as the difference in electric pressure between the two ends of a conductor.

The unit for potential difference is Volt and it is represented by ‘V’.

Resistance: It can be defined as the property of a material which opposes the electric current to flow through it.

Generally it is represented by ‘R’ and the unit for the measurement of resistance is ohm.