Newton on Light Diffraction

Newton felt there were some properties a wave theory of light simply could not explain, such as diffraction. For example, diffraction is the property of waves that allow them to bend around objects and spread through openings. In the case of sound waves, it’s why a sound in one room can often be heard in another room farther away by someone not directly in the path of the oncoming sound; the sound wave travels from the one room, spreading out through the doorway into the other room where it’s then heard. Light doesn’t appear to behave this way, after all, you can’t see around corners – can you? The diffraction of light is usually unnoticeable because light waves have such short wavelengths – much smaller compared to the wavelengths of sound waves. Nonetheless, light will diffract if the opening is small enough.

Sound Waves, Diffraction, and Propagation

A sound wave will often travel from one room to another spreading out though an adjacent doorway where it’s then heard. This is an example of the wave property known as diffraction.

Waves and Diffraction

A lower pitch sound, that is a sound wave with a longer wavelength (lower frequency), will diffract (or bend) around an object more than a higher pitch sound (a sound wave with a shorter wavelength and higher frequency). This means a lower pitch sound is more easily heard around an object that may be in front of the source of the sound than a higher pitch sound