KEY CONCEPT
Waves behave in
predictable ways.
BEFORE, you learned
NOW, you will learn
• Waves transfer energy
• Amplitude, wavelength, and
frequency can be measured
• How waves change as they
encounter a barrier
• What happens when waves
enter a new medium
• How waves interact with
other waves
STANDARDS
8–6.4 Summarize
the behaviors of waves
(including refraction,
reflection, transmission,
and absorption).
EXPLORE Reflection
How do ripples reflect?
PROCEDURE
VOCABULARY
reflection p. 457
refraction p. 457
diffraction p. 458
interference p. 459
1
Put a few drops of food coloring into the
pan of water.
2 Dip the pencil in the water at one end of
MATERIALS
• wide pan, half
full of water
• food coloring
• pencil
the pan to make ripples in the water.
3 Observe the ripples as they reflect off the
side of the pan. Draw a sketch of the
waves reflecting.
WHAT DO YOU THINK?
• What happens when the waves reach
the side of the pan?
• Why do you think the waves behave as they do?
Waves interact with materials.
COMBINATION NOTES
Use combination notes in
your notebook to describe
how waves interact with
materials.
You have read that mechanical waves travel through a medium like air,
water, or the ground. In this section, you will read how the motion of
waves changes when they encounter a new medium. For instance,
when an ocean wave rolls into a ship or a sound wave strikes a solid
wall, the wave encounters a new medium.
When waves interact with materials in these ways, they behave
predictably. All waves, from water waves to sound waves and even light
waves, show the behaviors that you will learn about next. Scientists
call these behaviors reflection, refraction, and diffraction.
What behaviors do all waves have in common?
456 Unit 4: Waves, Sound, and Light