There are two equipotential surafce as shown in figure. The distance between them is `r`. The charged of `-q` coulomb is taken from the surface A to B, the resultant work done will be

The figure showsn tow parallel equipotential surface A and B kept at a small distance 'r' a part from each other. A point chang of Q coumomb is taken from the surface A to B. The amount of net work done will be

Two charge +q and -q are placed at distance r. Match the following two columns when distance between them is charged to r'.

If the distance between two point charges is doubled and magnitude of charges are also doubled, the Coulomb's force between them will be

Work done in moving a charge q coulomb on the surface of given charged conductor of potential V is