The why's and wherefores come directly from a consideration of Maxwell's equations. If he doesn't understand Maxwell's equations, then he should get some books and start reading !

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

James Clerk Maxwell was one of the greatest mathematical physicists of all time. Einstein acknowledged his own debt to Maxwell.

Faraday however, 25 years or more before Maxwell, was actually working towards the same concepts. Faraday did not have the maths to describe it in the integral form of Maxwell (who didn't use the vector calculus used today) Faraday did a remarkable thought experiment (noted in contemporary records), which led him, 60 years before Hertz proved it, to determine that electrical signals can a.) propagate through free space and b.) do so at the speed of light.

Steve