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Hi folks,

Huygens principle is not really new to me but I just realized there is something I don't understand with it. Take a single 1D slit with a coherent incident plane wave. It seems that the number of wavelets in the slits is ##n = l/\lambda##, where ##l## is the length of the slit, and ##\lambda## si the wavelength of the light. Why is it so ?

For instance, Wikipedia gives two exemples.

- a slit of length 1 wavelength has 1 wavelet :

- while a slit of length 4 wavelength has 4 wavelets :

I'm looking more for some kind of intuituve explanation for the phenomenon, if there is one. I have a feeling that if we consider infinitely many wavelets in the slit, no matter it's size, they all interfere in such a way that they form a ##n## wavelets pattern. Maybe, I'm not sure.

Huygens principle is not really new to me but I just realized there is something I don't understand with it. Take a single 1D slit with a coherent incident plane wave. It seems that the number of wavelets in the slits is ##n = l/\lambda##, where ##l## is the length of the slit, and ##\lambda## si the wavelength of the light. Why is it so ?

For instance, Wikipedia gives two exemples.

- a slit of length 1 wavelength has 1 wavelet :

- while a slit of length 4 wavelength has 4 wavelets :

I'm looking more for some kind of intuituve explanation for the phenomenon, if there is one. I have a feeling that if we consider infinitely many wavelets in the slit, no matter it's size, they all interfere in such a way that they form a ##n## wavelets pattern. Maybe, I'm not sure.