Oscillations - Result Question 50
54. A simple pendulum has a metal bob, which is negatively charged. If it is allowed to oscillate above a positively charged metallic plate, then its time period will
[2001]
(a) increase
(b) decrease
(c) become zero
(d) remain the same
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Answer:
Correct Answer: 54. (b)
Solution:
- (b) We know that the time period (T)
$=2 \pi \sqrt{\frac{l}{g^{\prime}}} \propto \frac{1}{\sqrt{g^{\prime}}} \quad g^{\prime}=g _{\text{effective }}$
Since the negatively charged bob is attracted by the positively charged plate, therefore acceleration due to gravity will increase and time period will decrease.
