I was going through the standard derivation of intensity distribution in case of single slit diffraction
I don't understand why we equate the scalar summation of electric field phasors(or the length of the phasor arc) to the Electric field at central maxima i.e. $E_{m}$, wouldn't that imply that the wavelets reaching any point are equal in number?
This doesn't make sense to me as using the Fresnel-Huygens principle for any point on slit we can see that the wavelets reaching a point on the screen at a higher angle would be comparatively lower than at a lower angle,in simplified terms due the the same arc length being distributed to a larger length of screen for higher angles.
