Question
Physics Question on Oscillations
A wooden block performs SHM on a frictionless surface with frequency v0. The block carries a charge +Q on its surface. If now a uniform electric field E is switched-on as shown, then the SHM of the block will be
of the same frequency and with shifted mean position
of the same frequency and with the same mean position
of changed frequency and with shifted mean position
of changed frequency and with the same mean position
of the same frequency and with shifted mean position
Solution
Frequency or time period of SHM depends on variable forces.
It does not depend on constant external force. Constant external
force can only change the mean position. For example, in the
given question mean position is at natural length of spring in the
absence of electric field. Whereas in the presence of electric
field mean position will be obtained after a compression of x0.
Where x0 is given by
Kx0=QEorx0=KQE
∴ Correct answer is (a).