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Light and Refraction

Light is energy that acts on our eyes. Without light, we
could not see.
Light radiates, or travels in straight lines in all directions
from its source. It consists of tiny particles called photons. The sun
is our most important natural light source.
Light waves travel faster through air than through water,
glass, or other substances. When a light ray passes at an oblique
angle from one material to another, its path typically appears to
bend. This is called refraction.
Differences in air temperature and atmospheric pressure
can do some funny things to light rays. Pavement on a hot sunny
day sometimes appears to be wet. But the sidewalk is as dry as a
bone. What you’re seeing is light refracted by hot air rising up
from the ground. This effect is called a mirage.
The Danish astronomer Ole Roemer proved in 1676 that
light takes time to travel from one place to another. Over the years,
improved instruments have helped scientists calculate the speed of
light more accurately, at about 186,282 miles per second (299,792
kilometers per second).

Comprehension Questions

I. Say which of the following statements are false and
which are true. Correct the false statements to make them
true.

1. Light acts on our eyes.
2. The Sun is artificial light source.
3. Light waves travel faster through glass than through air.
4. Differences in air temperature and atmospheric pressure
can do nothing to light rays.
5. Ole Roemer was a Spanish astronomer.

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