Page 59 - Science Course 3 (Book 2)

Mo10-L2b: How Does Light Interacts with Matter?

Intensity of Light The Sun’s rays slow down when they enter Earth’s
atmosphere and the light rays refract toward Earth’s
Intensity is the amount of energy that passes surface.
through a square meter of space in one second.
This refraction causes you to see the Sun even after
Intensity depends on the amount of energy a source it has set below Earth’s horizon.
emits and the light’s distance from the source.

The brightness of a light is a person’s perception of
intensity.
6% Refraction
11% Image of Sun
25%
100%

Actual Sun

Interaction of Sunlight and Matter Vision and Eye

As sunlight moves through Earth’s atmosphere, the Light enters the eye through the cornea, and other
particles in the air scatter the sunlight’s wavelengths. parts of the eye, including the cornea and the lens,
focus light onto the retina.
The Sun appears yellow because the blue wave-
lengths of light scatter and the remaining colors Cells in the retina absorb the light and send signals
appear yellow. about the light to your brain.

The Sun’s
rays in space

1

Earth’s
Atmosphere
6 2

Light changes speed
as it travels from one 3
medium into another. 4
5
If light enters a new
medium at an angle,
the light wave refracts,
or changes direction.

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