Thread: Electric field and Magnetic field

I was wondering when electric field and magnetic field are emitted from their source, what is needed to make both field perpendicular to each other??Just a sudden brainstorm after some reading on the velocity selector.
Any help?

Maxwell's equations dictate the nature of an electromagnetic wave. They state mathematically that a changing electric field will generate a changing magnetic field, and vice versa (In particular Faradays law of induction and Amperes law), and that the fields will regenerate each other, allowing the wave to propagate. They also state that the fields will be at right angles to each other.

http://en.wikipedia.org/wiki/Maxwell%27s_equations

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