Two insulated charged metallic spheres A and B have their centres separated by a distance of 50 cm in air (1) calculate the force of répulsion between them, if the charge on each is ` +5.0xx 10 ^(-8) C` (ii ) calculate the force of repulsion between them when the two spheres are placed in water. (dielectric constant of water is 81.0)

Explanation

` F = (9xx 10 ^(9) xx (5 xx 10 ^(8))^(2))/((50 xx 10 ^(-2))^(2))`
` = (9xx 10 ^(9) x (5xx 10 ^(-8))^(2))/((0.5)^(2)) =9 xx 10^(-5) N`
(ii)` F = (9 xx 10 ^(-5))/(81) = 1.11 xx 10 ^(-6)N`