Question

When light passes from air to glass, its speed ______ and when it passes from glass to water, its speed ______.

• A. decreases; increases
• B. remains constant; increases
• C. decreases; remains constant
• D. increases; decreases

Answer 1

The correct option is A decreases; increases

The correct answer is Option A - decreases, increases. As we studied, the speed of light in different mediums.

In vacuum/air = 3×${10}^8$ m/s


In glass = 2 ×${10}^8$ m/s.


In water = 2.25×${10}^8$ m/s
Hence, when light passes from air to glass, its speed decreases and when it passes from glass to water, its speed increases.