The speed of light will be minimum while passing through

A. Glass

B. Air

C. Water

D. Vacuum

The speed of light varies depending on the medium it travels through. To determine where the speed of light is at its minimum, we need to consider the refractive index of each medium listed: glass, air, water, and vacuum. The refractive index is a measure of how much light slows down in a medium compared to its speed in a vacuum.

Understanding the Refractive Index

The refractive index (n) is defined as the ratio of the speed of light in a vacuum (c) to the speed of light in the medium (v):

n = c / v

A higher refractive index indicates that light travels slower in that medium. Let's look at the refractive indices of the options provided:

• Vacuum: n = 1.00 (light travels at its maximum speed, approximately 299,792 km/s)
• Air: n ≈ 1.0003 (very close to that of a vacuum, so light travels almost as fast as in a vacuum)
• Water: n ≈ 1.33 (light slows down significantly compared to air and vacuum)
• Glass: n ≈ 1.5 (light travels even slower in glass than in water)

Comparing the Mediums

From the refractive indices, we can see that:

• In a vacuum, light travels at its fastest speed.
• In air, it is only slightly slower than in a vacuum.
• In water, light slows down more than in air.
• In glass, light is the slowest among the four options.

Final Analysis

Given this information, we can conclude that the speed of light is at its minimum when passing through:

Glass

This is because glass has the highest refractive index among the options, meaning light travels slower in glass than in air or water. Understanding how light interacts with different materials helps us grasp fundamental concepts in optics and physics.