# Does electric and magnetic field interact?

Can electric field or magnetic field interact with an Electromagnetic radiation? And can 2 electromagnetic radiations interact with each other? Rather than the interference effect.

• Hi, welcome to Physics SE! I think that this question shows insufficient prior research. Can you try mentioning some relevant things you're familiar with, to narrow it down to a conceptual difficulty we can help fix? If it helps, try doing some research using the word 'photon', and consider the fact that magnetic fields are created by moving charges. – user191954 Jun 25 '18 at 15:34
• Also, based on your phrasing, I would think that you're a bit confused about the nature of electromagnetic radiation and the relationship between electric fields, magnetic fields, and EM radiation. Try asking a question about those. It'll help you answer this question. But to partially answer this, interaction between photons is a big deal in particle physics. Under certain conditions, 2 photons of appropriately high frequencies can create an electron-positron pair, and that's just the most well-know phenomenon. There's much more. – user191954 Jun 25 '18 at 15:36
• The only correct approach is to write down the field equations and see what may change the field. Study this subject first. There is a domain of field strengths for which fields do not interact, but "add up" in the total field. – Vladimir Kalitvianski Jun 25 '18 at 15:54
• Please be a little bit more precise! Do you mean a classical view or and quantum mechanics view using photons? – abu_bua Jun 26 '18 at 13:48

1. Can electric or magnetic fields interact with an electromagnetic radiation?

• Electromagnetic radiation in terms of a classical interpretation is a combination of an electrical and magnetic field! Taking the classical Maxwell equations gives an explanation of how . The easiest way to see it is to look at the Poynting Vector.

$$\mathbf{S} = \frac{1}{\mu_0} \mathbf{E} \times \mathbf{B} \\ u = \frac{1}{2}\! \left(\varepsilon_0 \mathbf{E}^2 + \frac{1}{\mu_0} \mathbf{B}^2\right)\!, \\ \frac{\partial u}{\partial t} = - \nabla \cdot \mathbf{S} -\mathbf{J} \cdot \mathbf{E}.$$

The Poynting vector $\mathbf S$ represents the directional energy flux of an em-field. If the energy density $u$ (B and E field) changes in time, you got radiation and Joulsche's dissipation. This is what the last equation express.

• In case you mean: Can an em-radiation, interpreted as an amount of photons, interact with em fields, the answer is also yes. But it is much more difficult to explain, and you have to use a quantization version of Maxwell equations --> quantum-electrodynamics (QED).

2. Can two radiation interact with each other?

Yes, QED, and especially quantum field theory (2nd quantization) shows a lot of such examples.

• For instance the superposition is violated for strong fields! That means:

$$\mathbf E \ne \mathbf E_1 + \mathbf E_2$$

• Photon-photon scattering

You can find a good and short description on this link.

• In this answer I treat the two photon interaction ( contrasted to superposition of light beams, which are the non interacting part) physics.stackexchange.com/questions/242184/… – anna v Jun 26 '18 at 14:03
• @anna v: Thank you for this link, I will add it in my answer! – abu_bua Jun 26 '18 at 14:41