Tangential component of Electric field

Question

The above question i'm trying for so long but failed. This is from my class $12$ book(india).First of all i'm confused with tangential component of electric field, I mean why this? So far I've studied that electric field(Whether its own or someone's else) is always perpendicular to a charged body. So, there shouldn't be any tangential component. Could someone please explain me visually what's happening?

Strict Note: A class $12$ answer required. No complex statements please. Only for school childs.

Answer 1

This question relates to the surface of a charged body (not necessarily a conductor) where the electric field can have both normal and tangential components. The surface charge is static and the electric fields are static. Therefore the path integral of the electric field must be zero for any closed loop. Or equivalently, no energy is gained by a test charge being moved along this closed path. Therefore when you take a closed loop integral of the electric field in a plane vertical to the surface, where one path is parallel to the surface inside the body, the other parallel to the surface outside the body, and you make the distance of the parallel paths from the surface arbitrarily small, you will see that the path integrals of electric field inside and outside the surface enclosing the surface charge have to be opposite and equal. From this follow that the tangential fields at the surface must be equal.