Question

why is it necessary that the field lines from a point chargw placed in the vicinity of a conducyor normal tto the surface of the conductor at every point?

Answer 1

This is because, by its definition, a conductor should be equipotential surface itself. Hence either there must be no field lines in that region or field lines should be perpendicular to the conductor so that dV = -E.dr = 0.

But as point charge is present, electric field lines must be there. Hence , these field lines will be perpendicular to the conductor at every point on surface of conductor.

I hope it will help you....