Question

Two point charges Q and -2Q are placed at some distance apart. If the electric field at the location of Q is E, then the electric field at the location of -2Q will be

• A. $\frac{-E}{2}$
• B. $\frac{-3E}{2}$
• C. - E
• D. - 2E

Answer 1

The correct option is A $\frac{-E}{2}$

The electric field (E) at the location of first charge Q is given by $E=k\frac{-2Q}{r^2}$ where r is the distance between two charges. The electric field $\left(E_1\right)$ at the location of (-2Q) is given by $E_1=k\frac{Q}{r^2}$
From equations (1) and (2)
We get $\frac{E_1}{E}=-\frac{1}{2}$ or $E_1=-\frac{E}{2}$