Question

What is the ratio of the velocity of red color light to the velocity of the violet color of light in a vacuum?

Answer 1

Our eyes can see a wide range of visible light hues. Sunlight is a complex blend of hues. The sun's light seems white to human eyes. The colors are all in white light, yet they're all messed up. A prism may be used to see all of the colors independently. A triangle-shaped prism is a triangle-shaped fragment of glass or plastic. Red, orange, yellow, green, blue, indigo and violet are the colors of the rainbow in order. The initial letters of Roy G. $Biv$ is remembered by many people.

Complete step by step answer:
In a vacuum, red and violet light (=single photons or photon packets) travel at the same speed. Although red light has a lower frequency than violet light, the wavelengths are identical.
As a result, at least in a vacuum, the speed of both colors of light is the same.
Except at specific wavelengths, when the photon initiates an energy change in the atoms it encounters, the greater the photon's frequency, the slower it will be. Consider a spinning item as a photon. The longer it interacts with an atom and so slows down, the higher the frequency of its spinning motion. Violet light moves slower through air or water than red light because of this.
Therefore, the required ratio is $1:1$.

Additional information:
Example:
The different hues of light travel at different rates inside the prism, which allows it to work. Because light travels at different speeds, it bends in various ways, resulting in a dispersion of hues rather than a mixture. Violet is the slowest, so it's on the bottom, and red is the fastest, so it's on top. That is because the slower traveling waves have a higher index of refraction (the ratio of the speed of light in a vacuum to the speed of light in a substance) (i.e., violet). Violet light is the most distorted due to its higher index of refraction, while red light is the least bent due to its lower index of refraction, and the other colors lie somewhere in between. When there is a lot of water in the air, such as after a rainstorm, the water droplets act as a prism and can create a rainbow. Rainbows have a circular shape due to the spherical prisms (raindrops) that created them.

Note: Different wavelengths of light travel at the same speed in a vacuum, c. Light velocity for different wavelengths is different in other mediums, such as air, water, and glass, due to dispersion, i.e., the refractive index is a quantity related to the wavelength. For all wavelengths, the refractive index in a vacuum is$1$. In other media, the refractive index is more than one and is proportional to wavelength.