Question

A particle is having a charge of 2.0*10-4C is placed directly below and at a separation of 10 cm from the bobof a simple pendulum at rest. The mass of the bob is 100g. What charge should the bob be given so that the string becomes loose.

Answer 1

this may help u.......this may work out...

Answer 2

Answer:

Explanation:

We have been given the mass which is 100g,charge which is 2×10^-4 and the separation is 10 cm

As string looses force will be equal to mass × gravity

By equating force equal to mass × gravity

F×mg

kq1×q2/r^2=10^-1×9.8

By keeping all the values

q2=10^-1×9.8×10^-2/2×10^-4×9×10^9

q2=~5.4×10^-9