Question

A metallic sphere has a charge of 10uC. A unit
negative charge is brought from (A) to (B), both
100 cm away from the sphere but (A) being
east of it while (B) being on west. The net work
done on the unit negative charge is
(1) Zero
(2) 2/10 joules
(3) -2/10 joules
(4) –1/10 joules​

Answer 1

The net work done is zero
The metallic sphere forms an equipotential surface at a radius of 100 cm from the sphere.
Since the unit negative charge moves keeping the radius with the sphere constant, it moves on that equipotential surface yeilding work done as zero :)