A charged bead is capable of sliding freely through a string held vertically in tension. An electric field is applied parallel to the string, so that the bead stays at rest at middle of the string. If the electric field is switched off momentarily and switched on

Options

A. The bead moves downwards and stops as soon the field is switched on
B. The bead moves downwards when the field is off and moves upwards when the field is switched on
C. The bead moves downwards with constant acceleration till it reaches the bottom of the string
D. The bead moves downwards with constant velocity till it reaches the bottom of the string

Answer

(a)

Explanation

If the electric field is switched off momentrily and switched on ,then the bead moves downwards and stops as soon the field is switched on.