Question

What do you need to find the intensity of an electromagnetic wave?

Both the electric and magnetic field strengths.
Either the electric or magnetic field strength.
Only the electric field strength.
Only the magnetic field strength.

Answer 1

To find the intensity of an electromagnetic wave, you need both the electric and magnetic field strengths.

Step-by-step explanation:

To find the intensity of an electromagnetic wave, you need both the electric and magnetic field strengths.

Algebraic manipulation of the relationships B = E/c and ε = 1/μoc² produces the relationship Iave = (1/2)εc(B² + E²).

Therefore, having either the electric or magnetic field strength alone is not sufficient to determine the intensity of an electromagnetic wave.