Question

explain why the potential difference across the terminals of a cell is more in an open circuit and reduced in a closed circuit

Answer 1

Because the battery used in the circuit is a source of potential difference and it only works when the circuit is closed.

Answer 2

Explanation:

In electrical engineering, ground or earth is the reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the earth. Electrical circuits may be connected to ground for several reasons.