Question

two charges spheres are separated at a distance d exert a force F on each other. If charges are doubled and distance between then is doubled then the force is
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Answer 1

Answer: F//2 ,F, 2F, 4F

I believe it is A.

Answer 2

Answer:

No change occurs in Force.

Explanation:

Given are two charged spheres separated by distance d and exert a force F on each other.

According to Coulombic Force law,

$F=\frac{KQ_{1} Q_{2} }{d^{2} }$

When we double the charges on each sphere and also double the distance between them then the new resultant force is given as,

$F_{res}=\frac{K\times 2Q_{1}\times 2Q_{2} }{(2d)^{2} }\\F_{res}=\frac{KQ_{1}Q_{2} }{(d)^{2} }=F$

Hence, Force remains unchanged on the spheres when charges on them is doubled and distance is also doubled.