Question

1. Two small spheres, each of mass 2.00g, are suspended by light strings 10.0 cm in length Fig. A uniform electric field is applied in the x direction. The spheres have charges equal to -5.00 * 10-8 C and +5.00 * 10-8 C. Determine the electric field that enables the spheres to be in equilibrium at an angle =10.0°.

Answer 1

$$qE-k\frac{q^2}{(2l\sin{10})^2}=mg \tan{10}\\ (5\cdot10^{-8})E-(8.99\cdot10^{9})\frac{(5\cdot10^{-8})^2}{(2(0.1)\sin{10})^2}\\=(0.002)(9.8) \tan{10}\\E=4.42\cdot10^5\frac{V}{m}$$