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Electromagnetic waves

Electromagnetic waves

by Krishnan G -
Number of replies: 1

The rms value of the electric field of light coming from the Sun is 720 Newton per coloumb. The average total energy density of the electromagnetic wave is

a) 4.58 * 10-6 J m-3

b) 6.37 * 10-9 J m-3

c) 81.35 * 10-12 J m-3

d) 3.3 * 10-3 J m-3

 

Answer is given as a). Kindly give explanation.

In reply to Krishnan G

Re: Electromagnetic waves

by Manish Verma -

\({u_{av}} = \frac{1}{2}{ \ \varepsilon _0}{E_0}^2\)

\(Or,{u_{av}} = {\varepsilon _0}{E_{rms}}^2 = 8.85 \times {10^{ - 12}} \times 720^2\)