# Quick Conductor Question

1. Apr 21, 2007

### Swapnil

Why is it that BOTH electric AND magnetic fields are zero inside the conductor. My book says that the H-field is zero due to the fact that the E-field is zero but doesn't give any detailed explanation.

2. Apr 21, 2007

### marcusl

I think you already saw the post regarding zero E field. In an ideal conductor any H field will induce eddy currents at the surface that perfectly cancel the magnetic field inside.

3. Apr 21, 2007

### rbj

also, if you think about it using Maxwell's equations, if for a non-zero volume the E field is identically zero at all locations and in time, then there is no dE/dt as a source of a magnetic field. and because

$$\nabla \cdot \mathbf{B} = 0$$

there are no sole (monopole) sources of a magnetic field.

4. Apr 22, 2007

### Swapnil

Great! Thanks guys.

5. Apr 22, 2007

### vanesch

Staff Emeritus
Actually this is not entirely correct. According to *classical* EM, a perfect conductor cannot have any *change* in magnetic field, but it can have in principle a non-zero static magnetic field. It is a pure quantum effect that a superconductor cannot have a magnetic field inside. If it were a classical perfect conductor, it would simply "freeze in" the existing magnetic field at the moment of its transition to "perfect conductor".