Answer to Question #302179 in Electricity and Magnetism for Pankaj

Question

Two electric charges 2 µC and –1 µC are placed at a distance of 20 cm from each

other in vacuum. Locate the point on the line joining these two charges outside the

region between them at which the electric potential is zero with reference to the

positive charge.

Answer 1

$\varphi=0,$

$\varphi=\varphi_1+\varphi_2=\frac{kq_1}x+\frac{kq_2}{x-d}=0,$

$x=\frac d{1+\frac{q_2}{q_1}}=40~cm.$