Answer to Question #103129 in Electricity and Magnetism for Asif Sultan

Question

Two point charges q1=4uc& q2=9uc are placed 20cm apart.the electric field due to them will be zero on the line joining them at a distance of

Answer 1

For the equilibrium:

$$\frac{q_1}{(x)^2}=\frac{q_2}{(d-x)^2}$$

$$\frac{4}{(x)^2}=\frac{9}{(20-x)^2}$$

$$x=8\ cm$$

The electric field due to them will be zero on the line joining them at a distance of 8 cm from the first charge.