Three points X, Y and Z lie on the same straight line in an electric field

PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

Three points X, Y and Z lie on the same straight line in an electric field. A

2\,\text{C}

positive charge is moved slowly from X to Y with

+6\,\text{J}

of external work. The same charge is then moved slowly from Y to Z, and the external agent now performs

-4\,\text{J}

of work (i.e., the field does

+4\,\text{J}

of work on the charge). (i) Determine the potential difference

V_{YX}

. (ii) Determine the potential difference

V_{ZY}

. (iii) Using your answers above, find

V_{ZX}

and state which of the three points is at the highest electric potential. (iv) A

-2\,\text{C}

charge is now moved slowly from X to Z. Calculate the external work required and comment on its sign.