Electrostatics Question 714
Question: A pendulum bob of mass m carrying a charge q is at rest with its string making and angle $ \theta $ with the vertical in a uniform horizontal electric field E. The tension in the string is
Options:
A) $ \frac{mg}{\sin \theta }\text{ and }\frac{qE}{\cos \theta } $
B) $ \frac{mg}{\cos \theta }\text{ and }\frac{qE}{\sin \theta } $
C) $ \frac{mg}{\cos \theta }\text{ and }\frac{qE}{\sin \theta } $
D) $ \frac{mg}{qE} $
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Answer:
Correct Answer: B
Solution:
[b] In equilibrium,
$ T\cos \theta =mg $ ….(1)
$ T\sin \theta =qE $ ….(2)
From (1), $ T=\frac{mg}{\cos \theta } $ From (2), $ T=\frac{qE}{\sin \theta } $
