Explanation:

When white light passes through a prism, it undergoes a phenomenon called dispersion, where it splits into its component colors. This phenomenon is responsible for the formation of a spectrum of colors.

Refraction of Light:
When light travels from one medium to another, its speed changes, causing the light rays to bend. This bending of light is known as refraction. Refraction occurs because the speed of light is different in different mediums. The amount of bending depends on the angle at which the light enters the new medium and the refractive index of the medium.

Dispersion of Light:
Dispersion is the phenomenon where light is separated into its constituent colors due to the different refractive indices of different colors. Each color of light has a different wavelength and hence a different refractive index. When white light passes through a prism, it enters the prism at an angle and undergoes refraction. As a result of refraction, different colors of light are bent by different amounts, causing them to spread out and form a spectrum.

Formation of Spectrum:
When white light enters a prism, it is made up of a combination of all the colors of light - red, orange, yellow, green, blue, indigo, and violet. As the light passes through the prism, each color is refracted at a slightly different angle due to its different wavelength. This causes the different colors to separate and form a spectrum, with red light being bent the least and violet light being bent the most.

The order of colors in the spectrum is:
- Red
- Orange
- Yellow
- Green
- Blue
- Indigo
- Violet

Applications of Dispersion:
The phenomenon of dispersion is not only observed in prisms but also in rainbows, where water droplets act as tiny prisms. The colors we see in a rainbow are a result of dispersion. Additionally, dispersion is also used in devices like spectrometers, which are used to analyze the composition of light and identify different elements by their unique spectral patterns.

In conclusion, when white light passes through a prism, it undergoes dispersion, where it is split into its component colors, forming a spectrum. This phenomenon occurs due to the different refractive indices of different colors of light, causing them to bend at different angles when passing through the prism.