2 Waves Waves travel through a medium Can be solid, liquid, or gas Waves transport energyA wave is a repeating movement that transfers energy through matter or space.Light waves and radio waves do not need a medium in order to travel through space.
3 Types of WavesTransverse – matter moves at right angles as wave travelsEx: water moves up and down, ocean wave moves to the right
4 Compressional wave – matter moves in the same direction as wave travels Ex: pulse through a slinkySound wavesThe less dense area next to the compression is called the rarefaction.
6 Wave PropertiesWavelength – distance between one point on a wave and the nearest point just like itFrequency – how many wavelengths pass a fixed point each second (in Hertz)Amplitude – measure of energy in a wave, from the rest position to either the crest or the troughIn compressional waves, the denser the medium, the larger the amplitude.
8 Equation Time! v = velocity (in m/s) Lambda = wavelength (in m) f = frequency (in Hz or wavelengths/s)v = lambda x f
9 Calculating Wave Speed A wave has a wavelength of 2m and a frequency of 3Hz. What is its speed?
10 ReflectionReflection occurs when a wave strikes an object and bounces offAll waves can be reflectedThe Law of Reflection- The angle of incidence is equal to the angle of reflection
11 RefractionRefraction is the bending of a wave caused by a change in its speed as it moves from one medium to anotherThe greater the change in speed, the more the waves bends
12 Moving into a medium in which it slows down, the wave refracts toward the normal Ex: light moves from air to waterMoving into a medium in which it speeds up, the wave refracts away from the normalEx: light moves from water to air
13 DiffractionDiffraction occurs when an object causes a wave to change direction and bend around itRefraction= passing throughDiffraction= going around an objectThe larger the obstacle compared to the wavelength, the less diffractionAM radio waves diffract more than FM waves so reception is better
14 Interference When two or more waves overlap and combine 2 types: 1. Constructive- the waves add together2. Destructive- the waves subtract from each other
15 Standing WavesWaves of equal wavelength and amplitude, traveling in opposite directions, continuously interfere with each otherPlace where they cross and cancel each other are called nodesMusical instruments produce standing waves
16 ResonanceThe natural frequency of a bell’s vibration depends on the bell’s size, shape, and materialThe ability for an object to vibrate by absorbing energy at it’s natural frequency is called resonanceEx: tuning fork