Ch.12.less.12.how does light travel and interact with matter

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

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

3. Determine what is transparent, translucent
and opaque.

4. 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.

5. Distance traveled by light from sun to earth
=90 million miles
Light travels at very high speed.

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

7. Light travels in a straight line.

8. Distance between one peak
and the next in a wave.
Wavelength

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

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

11. Draw the sunlight rays falling on the objects.

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

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

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

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

18. How can we see images in mirrors?

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.

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

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

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

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

28. The colors of the spectrum.

29. Each color has a different wavelength.

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

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

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

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