Question

Two pith balls each weighing 19.6 x 10kg are suspended from the same - point A by two silk threads each 1.0 m long. The two pith balls have identical charge and repel each other making an angle 90° at the apex A. Calculate magnitude of each charge.​

Answer 1

Answer:

Figure shows the different forces acting on the pith-ball, i.e., Tension T in string, weight mg of the ball

and electrostatic force Fe.

By resolving Tension force, we write, T sine = Fe

________.(1)

__________ (2) T cose = m g

dividing (1) by (2), we get, tane = Fe / mg

Hence if q is charge on each ball, then Fe = q² 4π€ (0.2)² 10-³×9.8× 1

24

(3)

Using eqn. (3) and substituting 1/(4²) = 9×10⁹, we get

q=0.94x107c = 94 nC