Light appears to bend {diffraction}| around corners and edges. If light rays meet corners, corner re-radiates light in all directions, so some light goes to region behind edge. Wavelets add to form wavefront there. At most wavefront points, wavelets cancel each other, so light intensity is zero. At some wavefront points, sum is positive, and light appears behind edge at regular intervals. Shadows have diffraction patterns at edges.
sound
Diffraction is how people can hear sound around corners.
size
If obstacle or edge is smaller than wavelength, wave goes farther around obstacle or edge. If obstacle or edge is larger than wavelength, diffraction has smaller angle.
frequency
Higher-frequency light and sound have smaller diffraction, because wavelengths are smaller. Lower-frequency light and sound bend more.
Physical Sciences>Physics>Wave>Diffraction
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Date Modified: 2022.0224