# Electromagnetic radiation effect on electric field?

• B
Hi, just trying to better understand this concept of electromagnetic radiation.

My understanding thus far is that it is a traveling disturbance in the electric field. This picture here seems to help me see what is happening:

My understanding of the electric field thus far is that at any given point in space, there is a magnitude and direction which will determine the force acting on a charged particle at that point. That magnitude in direction is computed as the sum of all contributions from other nearby particles (I guess either protons or electrons), based on their sign +/- and their position wrt to that point. Often I've seen the electric field be represented as this grid of pointing vectors. All that I think makes sense to me.

Anyway, back to my question. So what does this traveling disturbance through this grid of pointing vectors actually do? Does it affect both the magnitude and direction of the vectors? That gif I linked just shows a wave propagating, it doesn't show how it affects the electric field. Since each point on the electric field has both a direction and a magnitude, there are 2 things it could affect. My guess right now is that it just affects the magnitude of the electric field vectors, but it does it change their direction also?

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What you see in the gif IS the electromagnetic field. The blue guys are the B field and the red guys are the E field. They are completely connected with each other through the Maxwell equations. If - from e.g. a fixed charge in the neighborhood - there is a static electric field you can simply add up the vectors from that field and the E vector of the passing electromagnetic wave.

• Dace123 and davenn
Thanks for the reply, would the following description be accurate? Electromagnetic radiation is just a by-product of oscillating a charged particle. That is, when you move a charge, it changes the electric field, but that change in the electric field propagates outward from the charge at the speed of light, it doesn't change every point on the electric field immediately. If you move the charge up and down, this creates a wave pattern.

Is the gif I linked basically doing the exact same effect as this simulation, when you press the "sinusoidal" button?