1. WAVES

2. Types of Waves Mechanical Electromagnetic Longitudinal Transverse
Surface
Electromagnetic

3. WAVES a disturbance that transfers energy
Carries energy from one place to another
Classified by what they move through (called a medium)
Mechanical Waves (need a medium) the energy is transferred by vibrations of medium (medium = matter) Ex. ocean waves move through water, seismic waves, sound waves
Electromagnetic waves (do not need medium) the energy moves through disturbances in the electromagnetic field. Ex. light waves, radio, cell towers
Physics The act or process of propagating, especially the process by which a disturbance, such as the motion of electromagnetic or sound waves, is transmitted through a medium such as air or water.
A medium is a substance or material which carries the wave

4. Energy of waves
By definition, waves transfer energy. The energy spreads out as the wave travels. The bigger the wave the more energy it has.
Stand right by some speakers – how does it sound?
Look directly into a light – how does it look?

5. MECHANICAL WAVES
require a medium (the material through which the disturbance is moving) to transmit energy
travel through & gradually lose energy to that medium
Examples:
water, sound, rope, & spring waves
Mechanical Media:
water, air, rope, spring
Making a pulse

6. MECHANICAL WAVES Classified by how medium vibrates
           
           
Classified by how medium vibrates
Pulse = direction of energy transfer
Vibration = direction of vibration of medium relative to pulse
3 types:
Longitudinal,
transverse,
surface

7. MECHANICAL WAVES Classified by how medium vibrates Longitudinal Waves:
Vibration is in the same direction as wave pulse (parallel to wave pulse)
Transverse Waves:
Vibration is at 900 (right angles) to wave pulse
Surface Waves:
Vibration is circular
Ex/ Ocean waves; seismic waves

8. LONGITUDINAL WAVES
Vibration is parallel to the direction of the motion of the wave
Back and forth (compression & rarefraction)
Also called compression or pressure wave
Examples:
P-type earthquake waves
Sound waves
Rarefraction (expansion)
Compression

9. TRANVERSE WAVES Sideways or up & down Examples:
           
Vibration is perpendicular to the direction of the motion of the wave
Sideways or up & down
Examples:
S-type earthquake waves
Electromagnetic (EM) or light waves

10. Waves describe the Earth
P waves move through solids & liquids
P waves move through solids & liquids
S waves move through solids only!!!
Are these MECHANICAL WAVES????
YES!! Seismic waves need a medium (the earth!)

11. WAVE STRUCTURE CREST (peak) AMPLITUDE resting to max peak WAVELENGTH
TROUGH

12. CHARACTERISTICS OF WAVES
Crest
highest point of a transverse wave
Trough
lowest point of a transverse wave

13. AMPLITUDE Distance between “rest & crest” or “rest & trough”
Gives indication of “power” or “strength” of wave (magnitude of earthquake = Richter scale)
Does not affect velocity of wave
Determines loudness (sound) or brightness (electromagnetic wave)

14. WAVELENGTH 
Distance between any two repeating points on a wave crest-crest, trough-trough, expansion-expansion, compression-compression
Determines what colors we see; what notes we hear (pitch)
Shorter wavelengths have more cycles per minute because they aren’t as long

15. VELOCITY v the rate at which the energy travels; speed & direction
Depends on medium
Mechanical waves travel faster through dense mediums
EM Waves are faster through less dense mediums

16. Frequency ƒ
How often number of wavelengths that pass any point per second
measured in wavelengths/second or cycles/second Hertz (Hz) = number of wavelengths in 1 second
Frequency is related to velocity: v = ƒ 

17. PERIOD T
How long Amount of time for one wavelength to pass a point
Related inversely to frequency
Period = 1
Frequency
When an event occurs repeatedly, then we say that the event is periodic and refer to the time for the event to repeat itself as the period.

18. Internet resources
To test how well you understand go to
When an event occurs repeatedly, then we say that the event is periodic and refer to the time for the event to repeat itself as the period.