6.If a proton at a distance r due to an isolated point charge of q is

7.The work done in moving a charge of + 10  10-4 µC from infinity to 25cm from a charge of + 3  10-2 µC is

8.Electric potential of the earth is taken as

9.The unit for the amount of work done in moving a unit positive charge in an electric field is

10.If the potential difference between two points 2 cm apart in an electric field is 20 V, the electric field intensity between the points will be around