What is the SI unit of potential difference between two points in an electrical circuit?

Volt

The SI unit of electric potential difference is volt (V), named after Alessandro Volta (1745 –1827), an Italian physicist.

One volt is the potential difference between two points in a current carrying conductor when 1 joule of work is done to move a charge of 1 coulomb from one point to the other.

Therefore,

1 volt = \(\frac{\text{1 joule}}{\text{1 coulomb}}\)

1 V = 1 J C^–1

The potential difference is measured by means of an instrument called the voltmeter.