Waves PowerPoint Notes Part 1
Waves are everywhere in nature
§ Sound waves
§ Visible light waves
§ Radio waves
§ Water waves
§ Stadium waves
§ Earthquake waves
§ Waves on a string
§ Slinky waves
What is a wave?
§ A disturbance that transfers energy from place to place.
§
Waves transmit energy without transmitting matter.
§
This means that waves can move energy from one place to another without moving any matter
from one place to another .
The ball is the energy.
The girls symbolize matter.
The ball moves but the girls stay in the same place.
Wave Categories
1. Mechanical
2. Electromagnetic
Mechanical Waves
§ These waves require a medium.
§ A medium is the material through which a wave travels.
§ A medium can be a gas, liquid, or solid.
Examples:
o Water Waves
o Earthquake/Seismic Waves
o Sound Waves
o Waves That Travel Down A Rope Or Spring
Electromagnetic Waves
§
§
Waves that need NO medium.
They travel at the speed of light
in a vacuum.
Examples: §
§
§
Visible light
Radio
X-rays
Classifications or types of mechanical waves
1. Compressional/Longitudinal Waves
2. Transverse Waves
-based on how energy moves through them:
Longitudinal/Compressional Wave
§ The medium particles vibrate parallel to the motion of the pulse.
§ Matter vibrates in the same direction as the wave travels.
Example: Slinky
§ The metal of the slinky is the MEDIUM in that transfers the energy pulse of the wave.
§ The medium ends up in the same place as it started … it just gets disturbed and then returns to
it rest position.
Where the coils are close together are called compressions, the parts where the coils are spread out are called rarefactions.
Examples:
§ Sound waves
§ Some waves in a spring
§ Some seismic waves (primary waves to be exact)
Transverse waves
In a transverse wave the pulse travels perpendicular to the disturbance.
Waves that move the medium at right angles to the direction in which the waves are traveling.
Transverse means across. The highest parts are called crests the lowest parts are called troughs.
Examples:
§ Strings on a musical instrument
§ Waves on a rope
§ Some waves in a spring
§ Some seismic waves (earthquake waves- secondary waves, to be exact)
All Electromagnetic waves are transverse
o Transverse waves that can travel without a medium through empty space.