Consider two identical charges placed a distance `2 d` apart on the `x`-axis.The equilibrium of a positive test charge placed at the point `O` midway between them may be
(i) neutral
(ii) stable for displacement along the `x`-axis
(iii) stable for displacement along the `y`-axis
(iv) unstable for displacement along the `x`-axis

Options

A. stable for displacements along the x-axis
B. neutral
C. unstable for displacement along the y-axis.
D. stable for displacements along the y-axis

Answer

A, C

Explanation

a.,c.
If positive test charge is displaced along `x-`exis, then net force will always act in a direction opposite to that of displacement and the test charge will always come back to its original position. But if test charge is displaced along `y-` exis, if will never come back to its original position and will fly away along `y-`axis.