# At what aperture size is the diffraction of a water wave the greatest? Conflicting information!

This question should be a simple one, but I find conflicting infromation from different sources. At what aperture size is the diffraction of a water (or sound) wave the greatest? In my textbook, it has been said that:

Waves are diffracted when they pass through a gap or around the edge of an obstance. The effect is biggest when the width of the gap is equal to the wavelength of the ripples.

However, a Quora answer says something else:

[...] it's at a maximum (an outgoing spherical wave) for an infinitesimal pinhole. Google “Huygens's Principle”.

This stance is supported by another website:

When the gap size is smaller than the wavelength, more diffraction occurs.

Which is it? Is diffraction the greatest for an infinitesimally small aperture or for an aperture with the same width as the wavelength of the wave?

Note: Being a high school sophomore, I am not interested (because I may not understand) why this happens for light and in other non-GCSE level answers.

• Similar questions exist on Physics SE (I did see them), but they either don't have an answer, or don't answer the question. Commented Nov 13, 2021 at 5:39
• Huygens principle is about light. The wavelength of water waves and electromagnetic waves is very different, so there' is no conflict. Commented Nov 13, 2021 at 9:01