Question

two equal charges are separated by a distance of 2 metre in free space.calculate the magnitude of charge so that force between them is equal to weight of 20 kg child?
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Answer 1

f=kq^2/r^2 where f=mg =200 and k=9×10^9 solve this i hope you got your ans

Answer 2

weight of child = 20 * 9.8 N

coulombs force = kq^2/r^2

now, kq^2/r^2 = 20*9.8

q^2 =2*2*2*9.8/9*10^9

after calculations you will get

q = 9.33 *10^-5