How Does Wavelength Affect Intensity in Physics?

[frede89]

Homework Statement

Why is

I(x)= dP/dx*1/A

Where x is the wavelength lambda. P the power, A the area and I the intensity.

The Attempt at a Solution

I=P/A is all i know..

Thanks in advance

 

[frede89]

Can someone please tell me if this is the anwser:

I=P/A

I(x)=P/A (x)

I(x)= P/(x) * 1/A

I(x)= dP/dx * 1/A

The anwser must be something like this, right?