
Two forces will be acting on the mass m, gravity force and force by the electric field.
Thus, the effective force =(qE)2+(mg)2
From force equation, geff=g2+(mqE)2
Time period of the pendulum is (T)=2πgeffL
=2πg2+(mqE)2L
JEE Main 2019 — Physics Electromagnetism
A simple pendulum of length L is placed between the plates of a parallel plate capacitor having electric field E , as shown in figure. Its bob has mass m and charge q . The time period of the pendulum is given by:

Held on 10 Apr 2019 · Verified 6 Jul 2026.
2πg2+(mqE)2L
2π(g+mqE)L
2π(g−mqE)L
2πg2−m2q2E2L
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