Question

Five charges each q are placed at five corners regular pentagon. Distance from corner to the centre of pontagon is r. Then (K=(1)/(4pi epsilon_(0)))

Answer 1

Explanation:

Given two point charges exert a force F when placed r apart in air. When they are placed R apart inn a medium of dielectric constant K, the force between them is same. We have to find R.

For this, let q1 and q2 be two point charges. When these charges are placed in dielectric medium, then force is 4πε1R2q1q2

where ε0ε=K= dielectric constant of the medium.

So, new force =4πε0K1R2q1q2

when placed in air, F=4πε01r2q1q2

ε= permittivity of medium

ε0= permittivity of air

Given that force in both the cases is same; then 4πε1r2q1q2=4πε1