Q. The charges on two spheres are $+ 7\mu C$ and $- 5\mu C$ respectively. They experience a force $F.$ If each of them is given and additional charge of $- 2\mu C$, the new force of attraction will be
A) $F$
B) $F/2$
C) $F/\sqrt{3}$
D) $2F$
Explanation
(a) $F = \ \frac{1}{4\pi\varepsilon_{0}}\frac{( + 7 \times 10^{- 6})( - 5 \times 10^{- 6})}{r^{2}} = \ - \frac{1}{4\pi\varepsilon_{0}}\frac{35 \times 10^{12}}{r^{2}}N$
$F' = \ \frac{1}{4\pi\varepsilon_{0}}\frac{( + 5 \times 10^{- 6})( - 7 \times 10^{- 6})}{r^{2}} = \ - \frac{1}{4\pi\varepsilon_{0}}\frac{35 \times 10^{12}}{r^{2}}N$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.