Question 109: EM waves

Question

Intensity of sunlight is observed as 0.092 Wm
$-$2
at a point in free space. What will be the peak value of magnetic field at the point?
(${\varepsilon _0} = 8.85 	imes {10^{ - 12}}{C^2}{N^{ - 1}}{m^{ - 2}}$)

Accepted Answer

${I \over C} = {1 \over 2}{\varepsilon _0}.E_0^2$
$ \Rightarrow {E_0} = \sqrt {{{2I} \over {C{\varepsilon _0}}}} $
${{{E_0}} \over {{B_0}}} = C \Rightarrow {B_0} = {{{E_0}} \over C}$
$ \Rightarrow {B_0} = \sqrt {{{2I} \over {{\varepsilon _0}{C^3}}}}  = \sqrt {{{2 	imes 0.092} \over {8.85 	imes {{10}^{ - 12}} 	imes 27 	imes {{10}^{ + 24}}}}} $
$ = 2.77 	imes {10^{ - 8}}$ T

Answer

2.77 $	imes$ 10
$-$8
T

Answer

1.96 $	imes$ 10
$-$8
T

Answer

8.31 T

Answer

5.88 T

EM waves

Intensity of sunlight is observed as 0.092 Wm -2 at a point in free space. What will be the peak value of magnetic field at the point? ({\varepsilon _0} = 8.85 \times {10^{ - 12}}{C^2}{N^{ - 1}}{m^{ - 2}})

Choose the correct answer: