Problem: An isotropic source of electromagnetic radiation emits light that, when measured at 10 cm from the source, carries an electric field amplitude of 1.0x103 N/C and a magnetic field amplitude of 3.33x10-6 T.  (a) What is the average Poynting flux, Sav, through a sphere of radius 10 cm? (b) How much light-energy is emitted by the source per second? (c) If the source is 80% efficient at converting electrical power into light-energy, how much power must be supplied to the source?

Problem Details

An isotropic source of electromagnetic radiation emits light that, when measured at 10 cm from the source, carries an electric field amplitude of 1.0x103 N/C and a magnetic field amplitude of 3.33x10-6 T.

(a) What is the average Poynting flux, Sav, through a sphere of radius 10 cm?

(b) How much light-energy is emitted by the source per second?

(c) If the source is 80% efficient at converting electrical power into light-energy, how much power must be supplied to the source?