Question

The table shows the speed of light in three states of matter.

Material Speed (meters/second)
air 300,000,000
water 220,000,000
glass 200,000,000

At what point in time would the speed of light decrease?
A.
when the light travels from water to air


B.
when the light travels from air to water


C.
when the light travels from glass to air


D.
when the light travels from glass to water

Answer 1

The speed of light decreases when it enters a medium where it travels more slowly. Based on the provided speeds:

- Speed of light in air: 300,000,000 m/s
- Speed of light in water: 220,000,000 m/s
- Speed of light in glass: 200,000,000 m/s

Now let's analyze each option:

A. when the light travels from water to air: The speed increases from 220,000,000 m/s to 300,000,000 m/s (faster in air).

B. when the light travels from air to water: The speed decreases from 300,000,000 m/s to 220,000,000 m/s (slower in water).

C. when the light travels from glass to air: The speed increases from 200,000,000 m/s to 300,000,000 m/s (faster in air).

D. when the light travels from glass to water: The speed increases from 200,000,000 m/s to 220,000,000 m/s (faster in water).

The correct answer is **B. when the light travels from air to water**, as it experiences a decrease in speed when moving from air, where it is fastest, to water, where it is slower.