Two small spheres each carrying a charge q are placed r meter apart. If one of the spheres is taken around the other one in a circular path of radius r, the work done will be equal to 

1. Force between them × r

2. Force between them × 2πr

3. Force between them / 2πr

4. Zero

If a unit positive charge is taken from one point to another over an equipotential surface, then -

1. Work is done on the charge

2. Work is done by the charge

3. Work done is constant

4. No work is done

In the electric field of a point charge q, a certain charge is carried from point A to B, C, D and E. Then the work done

1. Is least along the path AB

2. Is least along the path AD

3. Is zero along all the paths AB, AC, AD and AE

4. Is least along AE

On rotating a point charge having a charge \(q\) around a charge \(Q\) in a circle of radius \(r,\) the work done will be:

Equipotential surfaces associated with an electric field which is increasing in magnitude along the x-direction are 

1. Planes parallel to yz-plane

2. Planes parallel to xy-plane

3. Planes parallel to xz-plane

4. Coaxial cylinders of increasing radii around the x-axis

In a certain charge distribution, all points having zero potential can be joined by a circle \(S.\) The points inside \(S\) have positive potential, and points outside \(S\) have a negative potential. A positive charge, which is free to move, is placed inside \(S.\) What is the correct statement about \(S\):

The diagrams below show regions of equipotentials.

Assertion : Potential difference between two points lying in a uniform electric field may be equal

                  to zero.

Reason : Points of line normal to electric field is equipotential line. 

Assertion : Two equipotential surfaces cannot cut each other. 

Reason : Two equipotential surfaces are parallel to each other.