Answer:t=0.134 s
Explanation:
Given
Area of wall over which wave strikes [tex]A=2\ cm^2[/tex]
Intensity of Electromagnet wave is [tex]I=\frac{c}{\mu _o}B_{rms}^2[/tex]
where [/tex]c[/tex]=speed of light
[tex]\mu _o[/tex]=Permeability of free space
[tex]B_{rms}[/tex]=RMS value of magnetic field
[tex]I=\frac{3\times 10^8}{4\pi \times 10^{-7}}\times (5\times 10^{-4})^2[/tex]
[tex]I=5.96\times 10^7\ W/m^2-s[/tex]
Average power is
[tex]P=I\cdot A[/tex]
[tex]P=5.96\times 10^7\times 2\times 10^{-4}[/tex]
[tex]P=11.92\times 10^{3}[/tex]
[tex]P=11.92\ kW[/tex]
time taken [tex]t=\frac{Energy}{Power}[/tex]
[tex]t=\frac{1600}{11.92\times 10^3}[/tex]
[tex]t=0.134\ s[/tex]
