This document discusses how light travels and interacts with matter. It explains that light travels from the sun to earth at a distance of 90 million miles. Light is made up of electric and magnetic waves, and travels faster in a vacuum than in other materials. The document defines transparent, translucent, and opaque materials and how they interact with light. It describes the formation of shadows and the law of reflection. Refraction of light is explained when light passes from one medium to another. The document also discusses the visible spectrum and how different colors of light have different wavelengths.

1. How does light travel
and interact with
matter?
Chapter 12: Lesson 3:

2. Distance traveled by light from sun to earth
=90 million miles

3. What is light made up of?
Electric waves Magnetic waves

4. Light can travel through vacuum.
Speed of light in vacuum is faster than its
speed in solid, liquid or gas.

5. Distance between one peak
and the next in a wave.
To calculate the speed of a wave:
Speed = Wavelength x frequency

6. Types of materials
Transparent
Translucent
Opaque
Allow most light to
pass through them.
Allow some light to
pass through them.
No light can pass
through them.

7. Determine what is transparent, translucent
and opaque.

8. When light does not pass through opaque
objects it forms SHADOWS.

9. Position of the SHADOW depends upon the
position of the light source.
Example:

10. Draw the sunlight rays falling on the objects.

11. Determine
the position
of the sun in
the following
pictures.

14. To change the size of the shadow, move closer
or away from the light source.

15. How do we see objects?
Light hits the objects and scatters (we see
objects).

16. Law of reflection:
Angle of incoming light = angle of reflected

17. How can we see images in mirrors?

19. Draw the
light rays
that helps
the girl
see her
image.

20. The image in a mirror is clear because most of
the light is reflected off the mirror’s smooth
surface.

21. Look at the spoon in the glass of water.
Is the spoon broken?

22. The spoon is not broken.
When light enters a different medium it bends and
when it is leaving it bends to the opposite side
again.

23. Bending of light while passing from on
substance to another is called
REFRACTION.

25. Draw the light rays to explain what is
happening.

26. WaterAir Air
Draw the light rays to explain what is
Refraction.

27. Sunlight is
white light,
when it
passes
through a rain
drop it is
divided into 7
colors.

28. When white light passes through a prism it comes
out as a spectrum (7 colors of rainbow)

29. The colors of the spectrum.

30. Each color has a different wavelength.

31. Red light has long wavelength.
Violet light has Short wavelength.
The way we see colored objects depends on
the color that is reflected.

32. Example:
The leaf is green so it absorbs all light and
green light is reflected.

33. The apple is red so it absorbs all light and red
light is reflected.

34. Predict what light is reflected for you to see
the color.