A point charge \(q\) is rotated along a circle in the electric field generated by another point charge \(Q\). The work done by the electric field on the rotating charge in one complete revolution is:
1. zero.
2. positive.
3. negative.
4. zero if the charge \(Q\) is at the centre and non-zero otherwise.

The energy density in the electric field created by a point charge falls off with the distance from the point charge as:
1. \(\dfrac{1}{r}\)

2. \(\dfrac{1}{r^2}\)

3. \(\dfrac{1}{r^3}\)

4. \(\dfrac{1}{r^4}\)

Two metal spheres of capacitances \(C_1\) and \(C_2\) carry some charges. They are put in contact and then separated. The final charges \(Q_1\) and \(Q_2\) on them will satisfy;
1.  \(\dfrac{{Q}_{1}}{{Q}_{2}}<\dfrac{{C}_{1}}{{C}_{2}}\)
2.  \(\dfrac{{Q}_{1}}{{Q}_{2}}=\dfrac{{C}_{1}}{{C}_{2}}\)

3.  \(\dfrac{{Q}_{1}}{{Q}_{2}}>\dfrac{{C}_{1}}{{C}_{2}}\)

4.  \(\dfrac{{Q}_{1}}{{Q}_{2}}<\dfrac{{C}_{2}}{\mathrm{C}_{1}}\)