Question

26. A particle having a charge of 20 x 10°C is placed
directly below and at a separation of 10 cm from the bob
of a simple pendulum at rest. The mass of the bob is
100 g. What charge should the bob be given so that the
string becomes loose?​

Answer 1

Answer:

Explanation:

mass of the bob=100g=0.1g ` <br> So, tension in the string <br> ` =0.1xx9.8=0.98N ` <br> for the tension to be 0, the charge below should repel the 1st bob <br> ` and F=mg ` <br> ` rArr (9xx10^9xxqxx2xx10^-4)/10^-2=10^-1xx10 ` <br> ` rArr q=5.4xx10^-9C`