Physics – 3.1 General properties of waves | e-Consult

Diffraction is more pronounced with longer wavelengths because it is a consequence of the wave nature of light and the principle of superposition. Longer wavelengths exhibit greater wave-like behavior, leading to a larger degree of bending around obstacles or openings.

Consider a wave approaching an edge. A shorter wavelength wave will pass around the edge with minimal bending, essentially continuing in a relatively straight line. A longer wavelength wave, however, will spread out more significantly as it encounters the edge. This is because the longer wavelength has more 'wavelength cycles' to 'fit' around the obstacle, resulting in a greater amount of bending.

Diagram:

In the diagram, the wave with the longer wavelength (Wave 2) clearly diffracts more around the edge than the wave with the shorter wavelength (Wave 1). The longer wavelength 'bends' more significantly, resulting in a wider spread of the wave. This spreading is what creates the diffraction pattern. The principle of superposition also plays a role; the waves diffracting around the edge interfere with each other, creating regions of constructive and destructive interference, which manifest as the bright and dark fringes in the diffraction pattern. The longer wavelength allows for a more pronounced interference pattern to develop.