Explanation:
It is known that formula for energy per unit area per unit time is as follows.
S = [tex]\frac{P}{A}[/tex]
= [tex]\frac{P}{\pi \times r^{2}} = \frac{4P}{\pi d^{2}}[/tex]
[tex]c \epsilon_{o} E^{2} = \frac{4P}{\pi d^{2}}[/tex]
E = [tex]\sqrt{\frac{4P}{\pi d^{2} c \epsilon_{o}}}[/tex]
Now, putting the values we will calculate the electric field as follows.
E = [tex]\sqrt{\frac{4P}{\pi d^{2} c \epsilon_{o}}}[/tex]
= [tex]\sqrt{\frac{4 \times 15 \times 10^{-3} W}{3.14 \times (2mm \times \frac{1m}{1000 mm})^{2} \times 3 \times 10^{8} \times 8.85 \times 10^{-12}}}[/tex]
= 1341.03 V/m
Now, we will calculate the average magnetic field as follows.
B = [tex]\frac{E}{c}[/tex]
= [tex]\frac{1341.03 V/m}{3 \times 10^{8} m/s}[/tex]
= [tex]4.47 \times 10^{-6}[/tex] T
= [tex]4.47 \mu T[/tex]
Thus, we can conclude that the average (rms) value of the magnetic field is [tex]4.47 \mu T[/tex].
