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?

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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?

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