waves.what is wave. How waves is formed?

Waves in Physics

1. WAVESWAVES

2. WAVESWAVES

Carries energy from one place to another Carries energy from one place to another

Classified byClassified by what what they move through they move through
1.1.Mechanical WavesMechanical Waves
the energy is transferred by vibrations of medium the energy is transferred by vibrations of medium
(medium = matter)(medium = matter)
ex/ ocean waves move through waterex/ ocean waves move through water
2.2.Electromagnetic waves (EM Waves)Electromagnetic waves (EM Waves)
the energy moves through disturbances in the the energy moves through disturbances in the
electromagnetic field.electromagnetic field.
a disturbance that transfers energy

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

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

5. MECHANICAL WAVESMECHANICAL WAVES
Classified by how medium vibrates
Pulse = direction of energy transfer


 
 
 
 
 
 
 
 
 
 
 


 
 
 
 
 
 
 
 
 
 
 
Vibration = direction of vibration of medium
relative to pulse
3 types:Longitudinal,transverse,surface

6. MECHANICAL WAVESMECHANICAL WAVES
Classified by how medium vibrates

7. TRANVERSE WAVESTRANVERSE WAVES

Sideways or up & downSideways or up & down

Examples:Examples:

S-type earthquake wavesS-type earthquake waves

Electromagnetic (EM) or light Electromagnetic (EM) or light
waveswaves
Vibration is perpendicular to the direction of
the motion of the wave

 
 
 
 
 
 
 
 
 
 
 

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

9. CHARACTERISTICS OF WAVESCHARACTERISTICS OF WAVES
Waves are described according Waves are described according
to their to their

AmplitudeAmplitude
measures DISPLACEMENTmeasures DISPLACEMENT
size of the disturbancesize of the disturbance

Wavelength Wavelength 
distance of a “repeating unit”distance of a “repeating unit”
Also called a cycleAlso called a cycle

Velocity Velocity vv
speed = how fast wave travelsspeed = how fast wave travels

10. AMPLITUDEAMPLITUDE

Distance between “rest & crest” or “rest & trough”Distance between “rest & crest” or “rest & trough”

Gives indication of “power” Gives indication of “power”
or “strength” of waveor “strength” of wave
(magnitude of earthquake = (magnitude of earthquake =
Richter scale)Richter scale)


Does not affect Does not affect
velocity of wavevelocity of wave

Determines loudness (sound) or brightness (EM wave)Determines loudness (sound) or brightness (EM wave)

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

12. VELOCITY VELOCITY vv

the rate at which the the rate at which the
energy travelsenergy travels; ;
speed & directionspeed & direction

Depends on mediumDepends on medium

Mechanical waves travel Mechanical waves travel
faster through dense faster through dense
mediumsmediums

EM Waves are faster EM Waves are faster
through less dense through less dense
mediumsmediums

13. Frequency Frequency ƒƒ

measured in measured in
wavelengths/second or wavelengths/second or
cycles/secondcycles/second
HertzHertz (Hz) = number of (Hz) = number of
wavelengths in 1 secondwavelengths in 1 second

Frequency is related to Frequency is related to
velocity:velocity: v v = = ƒ ƒ 

How oftenHow often
number of wavelengths that pass any point per secondnumber of wavelengths that pass any point per second

14. PERIOD TPERIOD T

How longHow long
Amount of time for one wavelength to pass a pointAmount of time for one wavelength to pass a point

Related inversely to frequencyRelated inversely to frequency
11
== 11
TT ff
PeriodPeriod
==
11
FrequencyFrequency