A uniform vertical electric field $E$ is established in the space between two large parallel plates. A small conducting sphere of mass $m$ is suspended in the field from a string of length $L$. If the sphere is given $a + q$ charge and the lower plate is charged positvely, the period of oscillation of this pendulum is :-
A uniform vertical electric field $E$ is established in the space between two large parallel plates. A small conducting sphere of mass $m$ is suspended in the field from a string of length $L$. If the sphere is given $a + q$ charge and the lower plate is charged positvely, the period of oscillation of this pendulum is :-
- A
${2\pi }\sqrt[]{{\frac{L}{g}}}$
- B
${2\pi }\sqrt[]{{\frac{L}{{g + (qE/m)}}}}$
- C
${2\pi }\sqrt[]{{\frac{L}{{g - (qE/m)}}}}$
- D
${2\pi }\sqrt[]{{\frac{L}{{{{\left[ {{g^2} - {{(qE/m)}^2}} \right]}^{\frac{1}{2}}}}}}}$
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