Two identical charges repel each other with a force equal to 10 mgwt when they are `0.6` m apart in air `(g = 10 ms^(-2))` . The value of each charge is

Options

A. `2 mC`
B. `2 xx 10^(-7) mC`
C. `2 nC`
D. `2 muC`

Answer

D

Explanation

`F = (1)/(4pieta_(0)) (q_(1)q_(2))/(d^(2))`
`therefore (10 xx 10^(-3))xx 10 = ((9 xx 10^(9))xxq^(2))/(0.6^(2))`
or `q^(2) = (10^(-1) xx 0.36)/(9 xx 10^(9))` = `(4)/(10^(12)) = 4 xx 10^(-12)`
or `q = 2 xx 10^(-6)C = 2 muC`.