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eep

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The problem is stated as follows:

"A laser provides pulses of EM-radiation in vacuum lasting [itex]10^{-12}[/itex] seconds. If the radiant flux density is [tex]10^{20}

{\frac{W}{m^2}}[/tex], determine the amplitude of the electric field of the beam."

So far, I figure that the period of one wave is [tex]10^{-12}[/tex] seconds. The instantaneous energy flux density is equal to [tex]\frac{E^2}{{\mu_o}c}}[/tex]. So an intergral of the instantaneous energy flux denisty over a period should equal the radiant flux density, no?

[tex]\int_{t=0}^{t=10^{-12}} \frac{E^2}{\mu_oc} dt = 10^{20} \frac{W}{m^2}[/tex]

Now, [tex] E = E_o cos({\omega}t) [/tex] and [tex]{\omega} * 10^{-12} = 2\pi[/tex]. So I should be able to integrate and solve for [tex]E_o[/tex]?