# Absorption of EM wave

## Homework Statement

An electromagnetic wave is incident on a surface which absorbs all the electric field. Use Maxwell’s equations to determine the magnetic field on the other side of the surface.

## The Attempt at a Solution

My initial thought was that ##B=0## as a varying B field would produce an E field. But then I thought we could still have a constant E field that has no oscillations. Is this even possible (it doesn't seem likely to me).

Many thanks

• Delta2

## Answers and Replies

Delta2
Homework Helper
Gold Member
With the assumption that nothing "extraordinary" is happening on the other side of the surface (for example we could have another EM wave there or a static E-Field from a charge distribution), all you can deduce from Maxwell's equations is that:

-the magnetic field will be constant with respect to time . This follows from Faraday's law, you are right that the B field isn't necessarily zero but just constant wrt time(no time varying)

-the magnetic field will be curl-free (irrotational, or equivalently its curl will be zero) . This follows from Maxwell's-Ampere law, since we know that the E-field is zero on the other side