 There are many ways waves act and interact. What is the difference here? › When we are discussing interaction of waves we need to know the difference between reflection, refraction, interference, diffraction, and so.

 Reflection: is when a wave hits a surface of a medium that it cant go through and bounces back. › Can anybody give me some examples of reflection that occur in everyday life?  Looking in the mirror  Sunlight glare from the hood of your car. › Law of reflection: states that the angle of incidence equals the angle of reflection

 Refraction : is the bending of waves as they enter a new medium at an angle. › Example. Who in here rides a skateboard?  Have you ever been riding down the sidewalk and gotten to close to the grass and had one of your front wheels go into the grass, what happened?  Your skateboard turned into the grass because of the change in speed of your front wheels.  The same thing happens with waves.

 Refraction only happens when a wave enters a medium at an angle. Because then one side of the wave enters the medium first, slowing it down, causing the wave to bend. › Have any of you put a stick into water and seen it “bend” or tried to pick something up in water and its not as close as it seems.  Why does a rainbow have all of those colors?  Because the white light is bent as it enters the water droplet.

 Diffraction : the bending of waves as they move around a barrier or pass through an opening. › Sometimes waves bend around stuff they cant get through, like an Island in the ocean, or a rocky point in a lake.

 What do you think of when we say interference? › What is wave interference?  Wave interference is : the interaction between two or more waves when they meet and take up the same space.  There are two types of interference.  Constructive and distructive

 Constructive interference: is when waves combine to make a wave with a larger amplitude. › These waves help each other. After they meet they continue as though they had never meet.

 Destructive interference :is when two waves combine to make a wave with a smaller amplitude. › These type of waves subtract their energy from each other, these type of waves basically cancel each other out.

 What is a seismic wave? › These are waves produced by Earthquakes.  Seismic waves include P waves, S waves, and surface waves. › P waves are longitudinal waves; P waves (or primary waves) move faster than the others. These waves are made up of compression and rarefactions of rock. These waves compress and expand the ground like a spring toy as they move through it.

 S waves; are transverse waves with crest and troughs. These are know as S waves or secondary waves. They shake the ground up and down and side to side as they move through it. These type of waves can’t travel through liquids. › This is how we know what the composition of the core is, because scientists directly on the opposite side of the Earthquake will only register P waves.

 Surface waves are a combination of transverse and longitudinal waves, that travel along the surface of the medium. These are the slowest of the seismic waves. › surface waves are what cause tsunamis when an Earth quake happens in the Ocean.