Question

A positively charged pendulum is oscillating in a uniform electric field pointing upwards. It's time period as compared to that when it oscillates without electric field is more How?

Answer 1

Step 1,

As we know that the time period of the pendulum is given as

$TimeperiodT=2\pi \sqrt{\frac{l}{g_{eff}}}$

Since the pendulum is positively charged and the electric field is in the upward direction

Step 2,

From the above figure, we can say that the value of the acceleration due to gravity will decrease.

So, $g_{eff}=(g-\frac{qE}{m})$

So we can write the time period as

$T^{\prime }=2\pi \sqrt{\frac{l}{g(1-\frac{qE}{mg})}}$

So the new time period is $T^{\prime }=2\pi \sqrt{\frac{l}{g(1-\frac{qE}{mg})}}$