Question

The magnitude of average value of S at a point is called as __________

(a) Amplitude of radiation

(b) Frequency of radiation

(c) Intensity of radiation

(d) Momentum flow

I have been asked this question during an internship interview.

This interesting question is from Poynting Theorem topic in chapter Electrodynamics of Engineering Physics II

Answer 1

Right answer is (c) Intensity of radiation

To explain: As the frequencies of electromagnetic waves are very high, the time variation of the Poynting vector is so rapid that we have to deal with the average value. The magnitude of average value of S at a point is called the intensity of the radiation at that point.