Question

Two point charges A and B of magnitude $+8 \times 10^{–6} C$ and $-8 \times 10^{–6} C$ respectively are placed at a distance d apart. The electric field at the middle point O between the charges is $6.4 \times 10^{4} NC^{–1}$. The distance ‘d’ between the point charges A and B is:

• A. 2.0m
• B. 3.0m
• C. 1.0m
• D. 4.0m

Answer 1

Answer: (B)

3.0m

Answer 2

Electric field at P will be E=$\frac{kq}{(d/2)^2}×2=\frac{8kq}{d^2}$

So, $\frac{8×9×10^9×8×10^{−6}}{d^2} =6.4\times10^4$

So, d = 3 m

$\therefore ,$ The correct option is (B): 3.0 m