a block of mass m havingcharge q is hanging vertically with the help of a spring constant k now vertical electric field E is switched on if spring attains its natural length when block comes at rest then strength of electric field is

see when it comes to rest accleration is zero so it is at rest so wehen equate force one forces are electrostatic and weight as spring is relaxed so the strenght of electic feild is mass*accleration due to grativty /CHARGE:ok kid that is enough for that question.