Question

Question 10 5 pts A radio antenna emits EM waves at a frequency of 100 MHz and intensity of 0.2 W/m2. What is the photon density in one cubic meter of the beam? 1.0E 12 photons/cubic meter O 1.0E 16 photons/cubic meter O 1.0E20 photons/cubic meter O 1.4E31 photons/cubic meter O 6.1E32 photons/cubic meter

Answer 1

Find the energy density using the intensity and then find the energy of one photon using the frequency. Divide the energy in 1 m³ by energy of photon to find the required solution as shown below

u a Ź 60 E2 Energy density but intensity I = 2 / CEE 1) (465) I= cu as ru יר I C = = 0.2 W/m² 3X 108 mis 6.67X10-83/m3 in one cubic meter energy E = 6:67 X10 J = energy of one phonon is Ep = hf : (6-626*10*34 559100x500) = 6.626 X 10-26 J So, no. of photons N= - EP 6.678208] 6.626 X 10-285 = 1:0X10 16 = I. 0 E 16 photons (cubic meter