A grating is able to spread white light out into a spectrum of colors because of the property of a. reflection. b. diffraction. c. dispersion. d. interference.

To understand how a diffraction grating spreads white light into a spectrum, it's crucial to grasp the concept of light diffraction. Diffraction occurs when light waves encounter an obstacle or a slit that is comparable in size to their wavelength. This causes the light waves to bend around the edges and spread out. For a diffraction grating, these are tiny slits arranged in a periodic pattern.

When white light hits the grating, it spreads out because different wavelengths (colors) of light are bent by different amounts. This separation of light into different colors is what creates the colorful spectrum you see. The grating creates multiple beams of light traveling in various directions, each corresponding to a different color. This is why diffraction is key to spreading white light into a rainbow of colors.

Spectral dispersion is the separation of light into its constituent colors. While diffraction gratings achieve this separation through diffraction, it's essential to distinguish it from other forms of dispersion, such as that caused by prisms.

In a prism, dispersion occurs because light of different colors travels at different speeds through the glass, causing them to bend by different amounts. In contrast, a diffraction grating uses the principle of light interference, where the structure of the grating causes the waves to overlap and separate based on wavelength.

So, while both a prism and a grating can disperse light into a spectrum, a grating does so due to the diffraction rather than refractive index differences.

Interference patterns arise when multiple light waves overlap and combine. At a diffraction grating, this happens in a structured manner due to the periodic arrangement of slits.

The light waves passing through the slits interfere with each other, creating constructive interference (bright spots) and destructive interference (dark spots). This organized pattern helps in forming the clear spectral lines you'd observe.

Constructive interference occurs when the path difference between the waves is an integer multiple of the wavelength, meaning the crests of the waves align perfectly. Destructive interference happens when the path difference is a half-integer multiple of the wavelength, causing crests to align with troughs and canceling out the light.

In a diffraction grating, these interference patterns are what give rise to the multiple beams of different colors, each corresponding to different angles, producing the beautiful spectrum.