Final answer:
In an electromagnetic wave, the electric field E and magnetic field H are related by the equation E = cB, with c being the speed of light. A strong electric field corresponds to a weak magnetic field due to the large value of c.
Step-by-step explanation:
The relation between electric field E and magnetic field H in an electromagnetic wave can be understood through the proportionality E = cB, where c is the speed of light in a vacuum, and B and H are related by the medium's permeability. Since the speed of light is a very large number, a relatively strong electric field corresponds to a relatively weak magnetic field in an electromagnetic wave.
This relationship is derived from Maxwell's equations and the fact that electromagnetic waves are transverse, meaning the electric and magnetic fields oscillate perpendicular to the direction of wave propagation.