Physics

Problem

Two identical small insulating spheres

A

and

B

are fixed

0.40\,\text{m}

apart on a smooth horizontal line. Sphere

A

carries charge

+q

and sphere

B

carries charge

+4q

. a. (i) Find the magnitude of the electrostatic force exerted by sphere

A

on sphere

B

. b. (ii) A third small sphere

C

carrying charge

-2q

is placed exactly midway between

A

and

B

. Determine the magnitude and direction of the net force acting on sphere

C

due to

A

and

B

together. c. (iii) All three charges are now simultaneously doubled in magnitude, and the distance between

A

and

B

is reduced to

0.20\,\text{m}

while

C

remains at the midpoint. Calculate the ratio of the new net force on

C

to the net force obtained in part (ii).