One end of a 10 cm long silk thread is fixed to a large vertical surface of a charged non-conducting plate and the other end is fastened to a small ball of mass 10 g and charge of `4 xx 10^(-6) C`. In equilibrium, thread makes an angle of `60^(o)` with the vertical.
(a) Find the tension in the string in equilibrium.
(b) Suppose the ball is slightly pushed aside and released. Find the time period of the small oscillations.
(Use `sigma=7.5xx10^(-7) C/m^2`)

Explanation

To solve the problem step by step, we will break it down into two parts as specified in the question.

### Part (a): Finding the Tension in the String

1. **Identify Given Values**:
- Length of the thread (L) = 10 cm = 0.1 m
- Mass of the ball (m) = 10 g = 10 × 10^(-3) kg = 0.01 kg
- Charge of the ball (Q) = 4 × 10^(-6) C
...