## January 27, 2015

### Senior Inter Physics Imp Questions - Electric Field and Potential

Q: Can there be electric potential at a point with zero electric
intensity? Give an example.
A: Yes. Ex: At any point inside a charged hollow conducting sphere
electric intensity is zero (E = 0) but electric potential is NOT Zero
(V ≠ 0).

Q: Can there be electric intensity at a point with zero electric
potential? Give an example.
A: Yes. Ex: At the mid point of an electric dipole electric potential
is zero (V = 0) but electric intensity is NOT Zero (E ≠ 0).

Q: What is equipotential surface? Why is an electric field always at
right angles to the equi - potential surface?
A: An equi-potential surface is a surface in an electric field on
which electric potential is same at all points.
If the electric field is not at right angles to equi-potential
surface, it would have nonzero components along the surface and work
would have to be done in moving an electric charge between two points
on the surface which is NOT correct.

Q: Define electric potential.
A: Electric potential: Electrostatic potential at any point in a
region of electric field is the negative of work done in bringing a
unit positive charge from infinity to that point.