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} $



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