Physics-
General
Easy
Question
A small sphere carrying a charge 
is hanging in between two parallel plates
by a string of length 
. Time period of pendulum is 
. When parallel plates are
charged, the time period changes to 
The ratio 
is equal to
- None of these
The correct answer is:
The motion of sphere is simple harmonic. It’s time period () is given by
(i)
where 
is length of string, g the acceleration due to gravity.
When sphere is placed in electric field. (
) force due to electric field acts on the sphere-1
where is charge on sphere.
Hence, resultant acceleration is
(ii)
Dividing Eq. (ii) by Eq. (i), we get
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