1. Chapter 15 : Characteristics of Waves
Lesson 1

2. What are waves?
A wave is a disturbance that transfers energy(the ability to do work or cause change) from place to place.

3. What carries a wave?
Most kinds of waves need something to travel through.
This material through which a wave travels is called a medium.
A medium can be a liquid, solid or gas.

4. Waves that require a medium to travel through are called Mechanical waves.
Waves that travel without a medium are called electromagnetic waves. Example: light from the sun(travels through empty space)

5. What causes a wave? Energy is required to make a wave.
Mechanical waves are produced when a source of energy causes a medium to vibrate.
A vibration is a repeated back-and- forth or up-and-down motion.
When a vibration moves through a medium, a wave results.

6. Mechanical waves can be classified by how they move.
There are 2 types of mechanical waves:
Transverse waves
Longitudinal waves (aka compressional waves)

7. Transverse Waves
Waves that move the medium at right angles to the direction in which the wave travels are called transverse waves.

8. Longitudinal Waves
A longitudinal wave moves the medium parallel to the direction in which the waves travel.
Ex: The coils in a spring toy(slinky) move back and forth parallel to the wave’s motion.
Sound is an example of a longitudinal wave.