Force between Two Charged Spheres'
What is the force between two small charged spheres having charges of ` 2 xx 10 ^(-7) C and 3 xx 10 ^(-7)` C placed 30 cm apart in air?

Explanation

Given , ` q_1 = 2xx 10 ^(-7) C , q_2 = 3 xx 10 ^(-7) C,`
` r = 30 cm = 30 xx 10 ^(-2) m = 0.3 m ` ,
` K =9 xx 10 ^(9) N-m ^(2) C^(-2) , F =? `
We have `, F = ( 1)/(4piin _0) (|q_1q_2|)/(r^(2)) = (k|q_1q_2|)/(r^(2)) " " [because (1)/(4piin _0) =k]...(i) `
Substituting the given values, in Eq. (i) we get
` F = ( (9 xx 10 ^(9) N-m^(2) C^(-2) )(2xx 10 ^(-7) C)xx (3xx 10 ^(-7)C))/((0.3m)^(2))`
` F = 6 xx 10 ^(-3) N`
This force is . respulsive , since the sphere have same charges.