CBSE Class 10 Answered

Voltag or electric potential difference or electric pressure is the difference in electric potential between two points. The voltage between two points is equal to the work done per unit of charge against a static electric field to move a test charge between two points. This is measured in units of volts (a joule per coulomb); moving 1 coulomb of charge across 1 volt of electric potential requires 1 joule of work.

The cause of electric pressure or potential difference is due to non-uniform charge distribution(either sign or magnitude)