1. Lesson one – What are waves?
Chapter 17 - Waves
Lesson one – What are waves?

2. Definition
A wave is a disturbance that transfers energy from one place to another without transferring matter. So, waves move energy through matter without moving the matter.
Waves can move in different patterns
Stones in a pond cause circular waves as ripples move outward from the source of energy
Wind causes waves on the ocean or lakes, where the wave moves in a linear pattern based on the direction of the wind

3. Parts of a wave

4. Movement of energy
When someone does a cannonball in the pool, it creates waves.
If you are floating on a tube, the energy will make you move up and down.
As the energy is transferred outward, it is spread over a greater area and diminishes in strength.
This type of wave is caused by energy that strikes the particles of water. Since those particles are moving faster, they will hit particles next to them
This is an example of a mechanical wave

5. Not to be confused with a friendly wave

6. See how the rope moves up and down while transferring the energy

8. Water waves are transverse waves. Sound waves are longitudinal waves.

9. While term wavelength applies in both cases, crest and trough do not.
The wavelength of a transverse wave is the distance from one crest to the next crest, or from one trough to the next trough.
The wavelength of a longitudinal wave is the distance between one are of compression to the next, or one area of rarefaction to the next.
Where the particles are close together, this is called a compression.
A rarefaction is the area where the particles are farther apart.

10. Mechanical waves need a medium to transfer energy
In a gas, molecules are farther apart, so they move more slowly and carry less energy than in other media.
In a liquid, molecules are closer together – waves can travel faster and transfer greater energy than in a gas.

11. When transverse waves collide….

12. Rogue waves
Also known as freak waves or monster waves, rogue waves are extremely large ocean waves. They are often created when several smaller waves come together to form one enormous wave. Rogue waves can be twice as tall as normal waves (or more) and can sink large ships.
Rogue waves are different from tsunamis, which aren’t caused by winds. Tsunamis are caused by seismic activity.

13. Earthquake waves
Earthquakes are caused by both transverse and longitudinal waves that move deep underground. Longitudinal waves move faster that transverse waves.

14. Electromagnetic waves
Electromagnetic energy travels through waves that can pass through a vacuum or through matter
Light, heat, radio waves, microwaves, and uv radiation are just some forms of energy carried by electromagnetic waves.
If it weren’t for electromagnetic waves, no energy from the sun would be able to reach Earth through the empty space between us and the sun.

15. Assignment: 1) Read pages 528 – 535
2) on page 536, answer question 1, 6, and 7. Note that the table in question 6 will need to be greatly enlarged to contain your information in a legible format.