Tuesday, April 21, 2009

Different sides of magnetic and electric field

Did you know that electric fields and magnetic fields are really two sides of the same coin?

This is why...

A static electric charge does not generate magnetic field. On the contrary, an electric current, or moving electric charges, 'generates' magnetic field. But motion is relative to the observer.

So if we have a static electric charge at the center of the room and you stood still - no magnetic field is observed. But then when you started running in the forward direction, the charge would seemed like it is 'moving' backwards. And, as above, a moving charge 'creates' magnetic field! Therefore, by running around the room, your motion could actually 'create' magnetic field, despite the fact that it is just a static charge in the middle of the room.

But surely, from the example above, you should know that we did not really 'create' anything. We are merely observing the effects of moving/accelerating against a static electric field, i.e. magnetic field radiation is just the observation of disturbance to the static electric field. Hence, electric field and magnetic field must be just two sides of the same coin!

There is a difference between observing static magnetic fields and observing radiating magnetic fields (as in the case of accelerating against a static charge). It is still an ongoing debate among physicist whether a uniformly accelerating static charge does indeed radiate. But if acceleration is not uniform, radiation is guaranteed. Those who are interested could search more information on the internet for this.

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