A sinusoidal electromagnetic wave has an average intensity of 100 W/m2W/m2. By what factor would the electric-field amplitude of the wave have to be increased in order for the wave to have an average intensity of 8100 W/m2W/m2

The electric field is increase to 80  so average intensity became 8100 .

Explanation:

Given :

Initial average intensity  

Final average intensity  

The average intensity is proportional to the square of the electric field.

∴  

    ∝

⇒  

So initial electric field is

Now intensity become so electric field is,

So final electric field  

So electric field increase by 80

are there answer choices to this question? this seems like a question where you have options to choose from.

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