Electrostatics Question 185
Question: Two similar spheres having $ +q $ and $ -q $ charge are kept at a certain distance. $ F $ force acts between the two. If in the middle of two spheres, another similar sphere having $ +q $ charge is kept, then it experience a force in magnitude and direction as [MP PET 1996]
Options:
A) Zero having no direction
B) $ 8F $ towards $ +q $ charge
C) $ 8F $ towards $ -q $ charge
D) $ 4F $ towards $ +q $ charge
Show Answer
Answer:
Correct Answer: C
Solution:
Initially, force between A and C
$ F=k\frac{Q^{2}}{r^{2}} $
When a similar sphere B having charge +Q is kept at the mid point of line joining A and C, then Net force on B is $ F _{net}=F _{A}+F _{C} $
$ =k\frac{Q^{2}}{{{( {r}/{2}; )}^{2}}}+\frac{kQ^{2}}{{{( {r}/{2}; )}^{2}}}=8\frac{kQ^{2}}{r^{2}}=8F $ .
