In the figure, two positive charges q2 and q3 fixed along the y-axis, exert a net electric force in the +x-direction on a charge q1 fixed along the x-axis. If a positive charge Q is added at (x, 0), the force on q1
1. shall increase along the positive x-axis.
2. shall decrease along the positive x-axis.
3. shall point along the negative x-axis.
4. shall increase but the direction changes because of the intersection of Q with q2 and q3.
A positive charge Q is uniformly distributed along a circular ring of radius R. A small test charge q is placed at the centre of the ring. Then,
a. | if q > 0 and is displaced away from the centre in the plane of the ring, it will be pushed back towards the centre. |
b. | if q < 0 and is displaced away from the centre in the plane of the ring, it will never return to the centre and will continue moving till it hits the ring. |
c. | if q < 0, it will perform SHM for small displacement along the axis. |
d. | q at the centre of the ring is in an unstable equilibrium within the plane of the ring for q > 0. |
1. (a, b, c)
2. (a, c, d)
3. (b, c, d)
4. (c, d)