What effect results from light traveling through a narrow slit and producing a pattern of light and dark bands?

When light travels through a narrow slit, it encounters a phenomenon known as diffraction. This occurs because light behaves as a wave. When the light waves pass through the narrow opening, they spread out and interfere with each other, resulting in a series of alternating light and dark bands on a screen placed behind the slit. This pattern is the defining characteristic of diffraction and illustrates the wave nature of light.

Interference, while related, is a broader concept that includes any situation where waves overlap and combine, resulting in constructive or destructive interference. However, in this specific context of light passing through a narrow slit, the primary effect observed is diffraction leading to the interference pattern. Therefore, the observed pattern is best attributed to diffraction, as it directly describes how waves bend around the edges of the slit and spread out, creating the characteristic light and dark areas.