The electrostatic force experienced by two charges q1 and q2 decreases but the net force which q1 is exerting on q2 remains same irrespective of madium. How is it possible?

hi himadri,

when u r talking about force in an isolated system be it with or without a medium containing two charges, u r actually talking about the net force itself . hence changing the medium will change the coulombic force  also. since it will change ε .

thank you.