Question

Four point +ve charges of same magnitude (Q) are placed at four corners of a rigid square frame as shown in figure. The plane of the frame is perpendicular to Z-axis. If a -ve point charge is placed at a distance z away from the above frame, the:

• A. -ve charge oscillates along the Z-axis
• B. It moves away from the frame
• C. It moves slowly towards the frame and stays in the plane of the frame
• D. It passes through the frame only once

Answer 1

The correct option is A -ve charge oscillates along the Z-axis

At the centre of the square frame, E = a and V = a constant positive value. The charge -q held above the frame will be attracted towards the center ). As it crosses O, a force begin to act on it in the upward direction. the charge -q begins to oscillate about 0 along the z-axis.