Physics

Problem

A point charge of

+12\,\mu\text{C}

is fixed at point

A

. Point

B

18\,\text{cm}

from

A

along a straight line. A point

P

AB

6\,\text{cm}

from

A

and is required to be a null point for a small test charge. Determine the magnitude and sign of the charge that must be placed at

B