The answer is "the earths rotation"
by the light bulbit converts through the electricity
Heat is technically the movement or more like vibration of the molecules. More thermal energy = more vibration
Well, they have the same speed when they're in the
same medium, and they both have the same physical
nature, since they're all electromagnetic radiation.
Fascinating factoid:
Many point-to-point radio systems use AM and FM at the same time
on the same signal, in order to carry more information on the signal.