Electrostatics Question 197
Question: 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 [MP PMT 2001]
Options:
A) 1 : 8
B) ? 8 : 1
C) 1 : 2
D) ? 2 : 1
Show Answer
Answer:
Correct Answer: B
Solution:
$ F\propto Q _{1}Q _{2} $
therefore $ \frac{F _{1}}{F _{2}}=\frac{Q _{1}Q _{2}}{Q _{1}^{’}Q _{2}^{’}}=\frac{10\times -20}{-5\times -5}=-\frac{8}{1} $
