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 (z<<L)then

(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

Correct option (a) -ve charge oscillates along the Z-axis

Explanation:

The negative charge oscillates, As the resultant force acts as a restoring force and cosθ component proportional to displacement. When it reaches the plane XY, the resultant force is zero and the mass moves down due to inertia.Thus, oscillation is set.

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