Question

Two charged bodies exert a force 0.8N on each other in a medium of relative permittivity 0.45.what will be the new force when they are placed in a medium of relative permittivity 0.9,assuming all other parameters remain unchanged.​

Answer 1

The electric force between charged bodies decreases by a factor equal to the relative permittivity, ie:

F ∝ 1/ε

F = electric force, ε = relative permittivity

Find the scaling factor of F due to the change in ε:

k = 1/(0.9/0.45) = 1/2 = 0.5

Multiply the original F by k to find the new F:

F = 0.8N×k

F = 0.8N×0.5

F = 0.4N