2Waves a disturbance that transfers energy through matter or a medium.
3Waves - waves transfer energy Most waves are caused Most waves are causedby vibrating objects.
4Types of Waves a wave that requires a medium to travel through. Ex. 1. Mechanical wave -a wave that requires a medium totravel through.Ex.Sound, ocean waves,earthquake waves
5Types of Waves a wave that does NOT require a medium to 2. Electromagnetic wave -a wave that does NOT require a medium totravel through.- these pass though by magnetic fields or electromagnetic fieldsEx.light
6Wave Forms1. Transverse waves -a wave that causes the particles to vibrate perpendicular to the direction the wave travelsEx.Stadium wave, radio waves,Heat waves,
7Wave Forms2. Longitudinal waves -a wave that causes the particles of the medium to vibrate parallel to the direction the wave travels.Ex.Sound wave, compression wave
8Wave Forms3. Surface waves -– particles move both perpendicular and parallel to the direction in which the wave travels.Ex.
9Sound Wave – require a medium to travel through. - longitudinal waves - causes the particles of the medium to vibrate parallel to the direction the wave travels.
10Wave Properties Determines the type and color of the wave. Wavelength- The distance between any one point on a wave to an identical point onnext wave.Determines the type and color of the wave.
11Wave Properties - crest The top of a wave - trough- The bottom of a wave
12Wave Properties Amplitude Half the distance from the crest and the trough.- determines the loudness of the sound.
13Wave Properties period - The time it takes a complete wavelength or wave oscillation to occur.- same distance as the wavelength.
14Wave Properties frequency - How many waves created in a given time; the number of cycles or vibrations in a given time.- SI label is Hertz (Hz)- determines the pitch of the sound.- high frequency = high pitch.
16Wave SpeedWave speed (v)- the speed of a wave is equal to wavelength divided by period, or frequency multiplied by wavelength.Two ways you can find wave speed:- wave speed (v) = wavelength/periodORv = frequency x wavelength
17Wave SpeedEx. Waves passing by a pier have a frequency of .5 Hz and a wavelength of 10 m. What is the wave speed?
18Determinates of wave speed: -The medium determines the speed of the wave.Ex. Sound: travels fastest in solid (15-20 x faster than air)travels fast in liquidtravels slowest in air (about 340 m/s)Ex. Light: travels fastest in empty space(c = 3 x108 m/s or 186,000 mi/s)slows down when it has to go through air or water
19Determinates of wave speed: Kinetic energy explains this.In air, molecules are far apart and won’t hit one another quickly.In solids, they are very close and will easily hit (vibrate) one another.
20Doppler EffectDoppler effect – an observed change in frequency of a wave when the source or observer is moving.
21Doppler EffectAs the ambulance is coming towards you, the siren sound is hitting you quicker, so the pitch is higher. As the ambulance is going away from you, the siren sound is going away, so it takes longer to hit your eardrum, so the pitch is lower.
22Wave InteractionsWhat happens when a wave meets an object or another wave?Waves can reflect, diffract, refract or interfere
23ReflectionReflection-The bouncing back of a wave when it meets a surface or boundaryExamples:Water waves reflect off the side of a boatLight waves reflect off the surface of a lake
24DiffractionDiffraction-A change in the direction of a wave when the wave meets an obstacle (ex. An opening)Examples:Sound waves diffract around cornersWater waves diffract around rocks
25RefractionRefraction-The bending of a wave when it passes between 2 mediums in which the speed of the wave differsExample: Straw in water
26InterferenceInterference-The combination of 2 or more waves that result in a single wave
27InterferenceConstructive interference-The combination of 2 or more waves that produce a wave with an increased amplitudeDestructive interference-The combination of 2 or more waves that produce a wave with a decreased amplitude