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Q & A: Can you push light with a magnetic or electric field?

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Most recent answer: 06/16/2014
Q:
We know that light is an electromagnet wave. So, can we deviate light with the help of a strong electromagnet? If we can deviate light with the help of a strong electromagnet then we can make something invisible. I want to know how that is possible.
- Razin A. Shaikh (age 15)
Navsari, Gujarat, India
A:

Hi Razin,

In general, you can't affect light by putting it through a strong electric or magnetic field. Electromagnetic fields exert forces on charged particles like electrons, but not on other fields. In fact, these fields can pass right through each other, which is why all the different light and radio and cell phone and other waves can just pass through each other and arrive at our eyes, radios, telephones, etc without getting all scrambled up.

There are a few special cases when these waves do influence each other. The most practical case is inside "nonlinear materials," for example certain crystals, which cause two overlapping light fields to interact weakly. This can be very practically useful (http://en.wikipedia.org/wiki/Nonlinear_optics), for example to split photons or combine photons together and change their frequency.

In principle, an electromagnetic field also contains energy and an associated gravitational field, so it does actually deflect light by a tiny tiny tiny amount, but realistically this effect is too small to be useful.

If you are interested in manipulating light to make an object invisible, you should look up cloaking devices, which aren't very practical yet, but are interesting in theory (http://en.wikipedia.org/wiki/Cloaking_device).

David

 


(published on 06/16/2014)

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