Which one of the following media has maximum speed of light?

Correct option is A

•  The speed of light is fastest in air among the listed options. In air, the speed of light is approximately 3 × 10^8 m/s (the same as in a vacuum, since air's refractive index is close to 1). However, in materials like water, glass, and diamond, light slows down because the refractive index of these materials is greater than that of air or vacuum. The refractive index is inversely related to the speed of light in the medium, so a higher refractive index results in a slower speed of light.

• The speed of light in a vacuum is the fastest possible speed, approximately 3 × 10^8 m/s, and it is used as the standard for measuring light speeds in other media.
• Refractive index is a property that describes how much light slows down when passing through a given medium. It is calculated as the ratio of the speed of light in a vacuum to the speed of light in the medium.
• Air has a refractive index of about 1.0003, meaning light travels almost as fast in air as in a vacuum.
• Water has a refractive index of about 1.33, which causes the speed of light to decrease to about 75% of its speed in a vacuum.
• Glass has a higher refractive index (approximately 1.5), causing light to travel slower than in water or air.
• Diamond has the highest refractive index among these materials (around 2.42), so the speed of light in diamond is the slowest among the options listed.

• Water, Glass, and Diamond: These materials have higher refractive indices than air, meaning that the speed of light is slower in each of them compared to air.