1. Unit 4 Section 2 Notes
Types of Waves

2. What is a Wave? Examples of Waves: Wave:
A disturbance that carries energy through matter or space.
Examples of Waves:
Sound you hear from your headphones
Earthquakes
Ripples in a pond

3. Mediums
A wave is not made of matter, but involves the movement of matter.
Most waves travel through a medium.
Medium: the matter through which a wave travels.
Examples:
Sound you hear from your headphones: Air
Earthquakes: Earth
Ripples in a pond: Water

4. Types of Waves Mechanical Waves: Most waves are mechanical waves
They require a medium (like water or air) to travel through.

5. Types of Waves Electromagnetic Waves:
Do NOT require a medium to travel through
Made of changing electric and magnetic fields, which radiate at the speed of light (3x108m/s)
This shows the wave traveling along one line, but it actually fills space.

6. Electromagnetic Waves
Anything that is part of the electromagnetic spectrum is an electromagnetic wave. That includes:
Radio waves
Microwaves
Infrared
Visible light
Ultraviolet light
X-Rays
Gamma Rays

7. Types of Waves
Mechanical Waves
Electromagnetic Waves

8. Waves do Work
We know that waves carry energy because they can do work:
Examples:
Water waves can do work on a leaf or a boat
Sound waves can do work on your eardrum

9. Waves do Work The larger the wave, the more energy it carries.
Example:
A cruise ship moving through the ocean may create waves big enough to move a fishing boat up and down a few meters.

10. Characteristics of Waves
If you go to a rock concert and stand next to the speakers, the sound waves may damage your ears. But if you stand 100 m away, the sound of the rock band is harmless. Why?
As waves travel outward, the spherical wave fronts get bigger, so the energy spreads out over a larger area.

11. Transverse and Longitudinal Waves
Waves are classified according to the direction in which particles in the medium move as a wave passes by; they can either move up and down or back and forth.
They are classified as either transverse or longitudinal.

12. Transverse Waves
Transverse wave: wave in which wave motion is perpendicular (up and down) to particle motion.
Examples:
A crowd doing “the wave”; individual people move up and down, but the motion travels around the stadium
Electromagnetic waves; electric and magnetic fields are perpendicular to each other

13. Motion of particles in a transverse wave
Wave travels to the right:
Particle motion
Wave motion

14. Longitudinal Waves (Compression Wave)
Longitudinal waves: Waves in which wave motion is parallel to the particle motion.
Example: Sound waves; as they move through the air, molecules in the air move backward and forward, parallel to the direction the sound waves travel.

15. Parts of Waves Transverse Waves Longitudinal Waves
Crests: high points of transverse waves
Troughs: low points of transverse waves
Compressions: crowded areas of longitudinal waves
Rarefactions: stretched out areas of longitudinal waves

16. Surface Waves Some waves are not simply transverse or longitudinal:
Surface Waves: Waves that move both perpendicular and parallel to the direction of wave motion.
Example: Waves on the ocean or swimming pool
This type of wave also occurs at the boundary between 2 different mediums, like water and air.

17. Surface Waves

18. Diagram of Types of Waves
Transverse
Longitudinal
Surface

19. Simple Harmonic Motion
A vibration that can keep on going without any interference.

20. Dampened Harmonic Motion:
A vibration that fades out as energy is transferred from one object to another