# Energy and momentum imparted by an EM wave

Tags:
1. Mar 25, 2016

### Titan97

1. The problem statement, all variables and given/known data
A plane electromagnetic wave is incident on a material surface. The wave delivers a momentum $p$ and energy $E$. Then which of the following is/are correct?

1) $p=0,~E=0$
2) $p\neq 0,~E=0$
3) $p=0,~E\neq 0$
4) $p\neq 0,~E\neq 0$

2. Relevant equations

None

3. The attempt at a solution
Is the answer (4)? When an em wave hits a surface, the electrons in it will start moving because of the electric field component. So it gets a momentum and some energy.

2. Mar 26, 2016

### Simon Bridge

Note:
If the question said that the wave delivers pizza P and Beer B then the correct statement would be $P\neq 0, B\neq 0$ ... it does not say how the wave delivers these things, perhaps it pushes a levitating train loaded with beer and pizza(?) - but that does not matter for the question as it is written.