Question

Earth receives 2 cal/min/cm^2 of solar energy. What is the value of \mid H\mid?

(a) 1.98 A/m

(b) 2.45 A/m

(c) 3.75 A/m

(d) 4.13 A/m

I got this question in exam.

I'm obligated to ask this question of Poynting Theorem topic in portion Electrodynamics of Engineering Physics II

Answer 1

Right option is (a) 1.98 A/m

To elaborate: We know, S = E X H. Here E and H would be in perpendicular direction.

Therefore, S = \(\mid E\mid \mid H\mid\)

Now, given S = 2 cal/min/cm^2

= 1400 J/sm^2

We know, \(\mid E\mid /\mid H\mid\) = 376.6

Therefore, \(\mid E\mid  = 376.6 \mid H\mid\)

Hence, 1400 = 376.6 \(\mid H\mid^2\)

\(\mid H\mid^2\)= 3.71

\(\mid H\mid\) = 1.98 A/m.