The electric force between a charged foam cup and a positively charged metal sphere is 2.12 newtons. if the charge on the cup is 2.0 × 10-6 coulombs and the charge on the metal sphere is 2.5 × 10-6 coulombs, what is the distance between the two? (k = 9.0 × 109 newton·meter2/coulombs2.

Answer : The distance between the cup and metal sphere is 0.1457 meter.

Solution : Given,

Charge on the cup =

Charge on metal =

Electric force = 2.12 Newton

coulombs constant, K =

Formula used : According to the Coulombs Law,

where,

F = Electric force

= coulombs constant

= Charge on the cup

= Charge on the metal

r = Distance between the two charged species

Now put all the given values in above formula, we get

By rearranging the terms, we get the value of 'r'

r = 0.1457 meter

Therefore, the distance between the cup and metal sphere is 0.1457 meter.