# Electromagnetic radiation in force field

Say I were to shine a laser in a particular direction and quickly turn it off. After a certain time, the radiation passes through a region of space. Some force field (e.g. electric or magnetic; assume gravity is negligibly small) is then turned on as the radiation passes, such that no mass or charge ever interacts with the radiation, only the "field" does. Would it change the behavior of the radiation, say compared to its earlier propagation through vacuum?

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Drakkith
Staff Emeritus
If I'm not mistaken, unless the strength of the field was unimaginably high, such as near a magnetar, the field would do effectively nothing.

If I'm not mistaken, unless the strength of the field was unimaginably high, such as near a magnetar, the field would do effectively nothing.
Would the electric fields add? Say the laser light E_rad varies from -5 to 5 newton per coulomb. The applied E_app is a constant -10 newton per coulomb. Then where the radiation passes, E_net varies from -15 to -5 newton per coulomb.

I would think the magnetic field stays the same, since it varies with the time rate of change of the electric field, which is not altered by applying a constant electric field.

Drakkith
Staff Emeritus
I'm not sure if it would add, but I'm fairly certain the light itself wouldn't be affected much, if at all.

Btw, doesn't a field carry energy? If so, shouldn't it affect the curvature of space-time like mass does?

The linearity of Maxwell's equations assures that no interactions between the two fields would occur.

Drakkith
Staff Emeritus
The linearity of Maxwell's equations assures that no interactions between the two fields would occur.
Other than any minute curvature of space due to energy of the field? If that happens I mean.

Electromagnetic radiation like the laser light is not effected by electric field.
The laser light will bend slightly i.e deflect from its path in a strong gravitational field due to general relativistic effects.

Btw, doesn't a field carry energy? If so, shouldn't it affect the curvature of space-time like mass does?

yes danmay it will be effected by spacetime curvature.

Other than any minute curvature of space due to energy of the field? If that happens I mean.
The linearity of Maxwell's equations assures that no interactions between the two fields would occur.
yes danmay it will be effected by spacetime curvature.
On second thought I think a field has to be accelerated for any energy to come into play.