When light passes through a prism the light bends. As a result, the different colors that make up white light become separated. This happens because each color has a particular wavelength and each wavelength bends at a different angle.

Answer:

When white light enters a prism, it gets split into its constituent colors, creating a beautiful rainbow effect. This phenomenon is known as dispersion. The reason behind this phenomenon lies in the principle of refraction and the different refractive indices for different wavelengths of each color.

Refraction and the Prism:

Refraction is the bending of light as it passes from one medium to another with a different refractive index. When white light enters a prism, it undergoes refraction twice - once when entering the prism and once when leaving it. The deviation of light depends on the refractive index of the medium through which it is passing.

Dispersion of Light:

1. Explanation of Option A:
- Different refractive indices for different wavelengths: When white light enters a prism, it consists of a combination of different colors with different wavelengths (red, orange, yellow, green, blue, indigo, and violet). Each color has a different wavelength, and hence, a different refractive index. As the light passes through the prism, it bends or refracts differently for each color due to their varying refractive indices. This causes the different colors to separate or disperse.

2. Explanation of Other Options:
- Option B: Each color having the same velocity in the prism is not the reason behind the dispersion of light. The velocity of light depends on the medium it is passing through, and different colors have different velocities due to their different wavelengths.
- Option C: The density of the prism material does not directly affect the dispersion of light. Dispersion is primarily caused by the variation in refractive indices for different wavelengths.
- Option D: Scattering of light refers to the random redirection of light by particles in the medium. While scattering can cause light to change direction, it is not the primary reason behind the dispersion of light in a prism.

Conclusion:

In conclusion, the dispersion of white light into its constituent colors when passing through a prism is primarily due to the different refractive indices for different wavelengths of each color. Each color bends differently as it passes through the prism, resulting in the separation and formation of a spectrum of colors.