Physics · Electric Charges And Fields · NEET
Only in the static (electrostatic) situation, when no current flows. If a battery drives a current through a wire, there IS a small field inside pushing the electrons. But when charges are at rest (no current), the free electrons have finished rearranging and E = 0 everywhere inside. NEET always asks the static case unless it says 'current'.
A conductor has free electrons that can move easily. If any field E existed inside, it would push these electrons (force F = qE). They keep drifting and piling up on the surface until the field they create exactly cancels the original field. Movement stops only when the total field inside becomes zero. So E = 0 is the equilibrium condition.
Yes to both. Inside the solid metal, E = 0. Inside an empty cavity (no charge placed in it), E is also zero, no matter the shape or the outside field. This is electrostatic shielding. The excess charge sits only on the outer surface, so the region enclosed by metal stays field-free.
Yes. The external field pushes electrons to one side, creating induced charges. These induced charges set up an opposite field inside that cancels the external one. The inside field is still exactly zero. This cancellation is why a metal box (Faraday cage) protects things inside from outside fields.
No, this is a classic trap. E = 0 means the potential does not CHANGE inside, so V is constant (the same at every interior point and on the surface). But that constant value is usually not zero. E = 0 tells you V is flat, not that V = 0.
Which of the following statements are correct? A. Inside a conductor, the electrostatic field is zero. B. Electric field at the surface of a charged conductor does not depend on its surface charge density. C. The interior of a charged conductor can have no excess charge in the static situation. D. At the surface of a charged conductor, the electrostatic field must be normal to the surface at every point. E. The electrostatic potential is zero everywhere inside a charged conductor.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
It is exactly zero everywhere inside the conducting material, whether the conductor is neutral or charged, and whether or not it sits in an external field. This holds only when no current flows (static condition).
Because free electrons keep moving as long as any field exists. They redistribute onto the surface and create an opposing field that cancels the original one. Equilibrium (charges at rest) is reached only when the net field inside is zero.
All excess charge moves to the outer surface. By Gauss's law, since E = 0 inside, any closed surface drawn in the interior encloses zero net charge, so no charge can stay inside the bulk.
Yes. If the cavity has no charge in it, the field inside the cavity is zero regardless of its shape or the outside field. This is called electrostatic shielding (the Faraday cage effect).
No. E = 0 means the potential is constant throughout the conductor and on its surface. That constant value is usually not zero for a charged conductor.
