NEETPhysicsElectrostatics
An uncharged solid metallic sphere is placed in a uniform external electric field. Which of the following statements correctly describes the electric field lines just outside its surface and the electrostatic potential inside the sphere?
Options
- AElectric field lines pass straight through the sphere parallel to each other, and the potential inside is zero
- BElectric field lines are tangential to the surface, and the potential inside is constant but non-zero.
- CElectric field lines are normal to the surface, and the potential inside is strictly zero.
- DElectric field lines are normal to the surface, and the potential inside is constant and equal to the surface
Correct answer
D. Electric field lines are normal to the surface, and the potential inside is constant and equal to the surface
Step-by-step solution
In electrostatics, the entire volume and surface of a metallic conductor are at the same electrostatic potential. Thus, a conductor in electrostatic equilibrium forms an equipotential volume, and its surface is an equipotential surface. Because the surface is an equipotential surface, the external electric field lines must be exactly normal (perpendicular) to the surface at every point. If they were not normal, there would be a tangential component of the electric field along the surface, which would cause charges