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  • In an Electromagnetic wave the amplitude of electric field is  . The frequency of wave is

In an Electromagnetic wave the amplitude of electric field is 1\frac{V}{m} . The frequency of wave is 5\times 10^{-14}Hz . The wave is propagating along z axis, the average energy density of electric field will be.

Option: 1

1.1\times 10^{-11}


Option: 2

2.2\times 10^{-12}


Option: 3

3.3\times10^{-15}


Option: 4

4.4\times10^{-14}


Answers (1)

best_answer

As we learned

The average energy density of EM wave -

U_{avg} = \frac{1}{2} \epsilon _{o}E_{o}^{2}

- wherein

E_{o} = Electric field amplitude

\epsilon _{o} = Permittivity of vacuum

 

The average energy density of the electric field =\frac{1}{2}\epsilon_{o}E_{rms}^{2}=\frac{1}{2}\epsilon_{o}E_{rms}^{2}=\frac{1}{2}\epsilon_{o}\left (\frac{E_{o}}{\sqrt{2}} \right )^2

=\frac{1}{4}\epsilon_{o}E^{2}=\frac{1}{4}\times 8.85\times 10^{-12}\times (1)^{2} = 2.2\times 10^{-12}J/m^{3}

 

Posted by

Ajit Kumar Dubey

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