Q. Two small conducting spheres of equal radius have charges $+ 10\ \mu C$ and $- 20\mu C$ respectively and placed at a distance $R$ from each other experience force $F_{1}$. If they are brought in contact and separated to the same distance, they experience force $F_{2}$. The ratio of $F_{1}$ to $F_{2}$ is
A) 1 : 8
B) $- 8:1$
C) 1 : 2
D) $- 2:1$
Explanation
(b) $F \propto Q_{1}Q_{2} \Rightarrow \frac{F_{1}}{F_{2}} = \frac{Q_{1}Q_{2}}{Q_{1}^{'}Q_{2}^{'}} = \ \frac{10 \times - 20}{- 5 \times - 5} = \ - \frac{8}{1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.