Question

) why is it necessary that the field lines from a point charge placed in the vicinity of a conductor must be normal to the conductor at every point.

Answer 1

This question is actually in the realm of physics.

It is the vector drawing representation of the invisible action of the charge, as defined by Faraday and has rules on how to depict the electric field lines.

I am mentioning a link here, which defines the subject and also has test questions at the end of the article.

Electric Field

Lineshttp://www.physicsclassroom.com/class/estatics/Lesson-4/Electric-Fields-and-Conductors

The second link perhaps will explain your query of why they are normal to the surface of the conductor - it is because the charge is in electrostatic equilibrium.

I sincerely hope this information meets your requirement.

Answer 2

Explanation:

As suggested by Marie Ampere, a current carrying conductor exerts a force when a magnet is placed in its vicinity. Similarly, a magnet also exerts equal and opposite force on the current carrying conductor. The direction of force over the conductor gets reversed with the change in direction of flow of electric current