JEE Advance - Physics (2011 - Paper 2 Offline - No. 2)
A wooden block performs $$SHM$$ on a frictionless surface with frequency, $${v_0}.$$ The block carries a charge $$+Q$$ on its surface . If now a uniform electric field $$\overrightarrow E $$ 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.
Explanation
The force exerted on charge +Q by the electric field $$\overrightarrow E $$ is
$$\overrightarrow F = Q\overrightarrow E $$
in the direction of $$\overrightarrow E $$. Since $$\overrightarrow F $$ is constant, a constant force is added to the applied force. Hence only the mean position will change.
The frequency will be same.
As $${v_0} = {1 \over {2\pi }}\sqrt {{k \over m}} $$ does not depend on the constant external force.
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