Question

The power of the electromagnetic wave with electric and magnetic field intensities given by 12 and 15 respectively is

(a) 180

(b) 90

(c) 45

(d) 120

The question was posed to me in unit test.

My doubt is from Power, Power Loss and Return Loss in portion EM Wave Propagation of Electromagnetic Theory

Answer 1

Right choice is (b) 90

Easy explanation: The Poynting vector gives the power of an EM wave. Thus P = EH/2. On substituting for E = 12 and H = 15, we get P = 12 x 15/2 = 90 units.