Unit 4: Waves Physics 313: Fall 2015 Agenda 10/26/2015 Review Unit 3 Exams Intro to Waves!! Wavy Lab Complete Analysis Questions for Lab Agenda 10/27/2015 Complete Wavy Lab Notes: Intro to Waves and Properties Intro Questions: Wavy Lab 1.What is the shape of a wave? 2.How do waves behave at free and fixed ends? 3.What happens when waves collide with one another? Learning Target #1: I can explain what a wave is and the source of all waves. What is a wave? A rhythmic disturbance that travels from one location to another and carries energy. Depending on the type of wave, may require a medium to travel through What is the source of all waves? Something that vibrates!!! Examples: Speakers, atoms, musical instruments What do waves carry / transfer? ENERGY What do all waves have in common? Same features among all waves Learning Target #2: I can explain the categories of waves. Based on movement of particles relative to direction wave travels Transverse Waves Particles move or Wave move Particles and wave move perpendicular to each other Transverse Waves - Examples Light waves Waves on a string Slinky waves Television waves microwaves Longitudinal Waves (pressure waves) Particles move to Waves move Particles and wave move parallel to each other Longitudinal Waves - Example SOUND WAVES Water Surface Waves Have characteristics of both longitudinal and transverse Ocean waves energy comes from storms Remember the Wavy Lab? What is a wave pulse? What is the medium? What is the source of the vibration? Compare the direction of the wave to the movement of the particle? (perpendicular or parallel? You have 5 minutes Answer questions Learning Target #2: I can explain the categories of waves. Based on if a medium is required Electromagnetic Examples: Light, radio, xrays, microwaves, tv What if visible light from the sun required a medium? Wave capable of transmitting energy without a medium (material) Energy is emitted and absorbed by the vibration of charged particles Mechanical Needs a medium (material) to transmit its energy Needs a medium (material) to transmit its energy Examples: Examples: Sound Water Strings Can you hear explosions/sounds in space? Can you hear explosions/sounds in space? Question 1: Compare the direction of particle motion to the direction of wave travel in a transverse wave. Particles in the medium (slinky) vibrate perpendicular to the direction of the wave. Question 2: Compare the direction of particle motion to the direction of wave travel in a longitudinal wave. Particles in the medium (slinky) vibrate parallel to the direction of the wave. Agenda 10/28/2015 Nspire: Note-Check from 10/27 Activity: Wave on a String PhET Building the Wave Equation Graphing Practice Notes: The Wave Equation Can you hear an explosion in space? Things to think about: What kind of wave is a sound wave? Does this wave need a medium? Does space contain a medium? Light is a wave, why can we see stars? Things to think about: What kind of wave is light? Does this light need a medium to travel through? Does space have a medium for light to travel through? Agenda 10/29/2015 Turn in Quarter 1 Project Wrap Up PhET Lab Complete Wave Equation PS No Homework if you finish PS What did we learn from the PhET? As wavelength increases, what happens to frequency? Does frequency ever reach zero? What kind of graphical relationship is there between frequency and wavelength? What does the slope of this graph tell us? Summary of relationships ** The only way to change the speed of a wave is to change the MEDIUM it moves through if wavelength remains constant** Changing the Speed of a Wave What happened to the speed of the wave if you changed the tension? Slinky demo. The only way to change the speed of a wave is to change the medium it moves through!! What are the common units of frequency and relationship to period? Example Problem A red light has a wavelength of 6.5 x m. If the speed of light is 3 x 10 8 m/s, what is the frequency of this light? Complete Wave Equation PS Agenda 11/2/15 Waves Warm-UP Check Wave Equation PS Homework Quiz Notes: Wave Interference Demo: Interference of Sound Practice: Interference PS Label the following features of a wave wavelength, amplitude, equilibrium point, crest, trough Question 1: How does the speed of a wave change if only the amplitude of the wave changes? The speeds of different pulses in the same medium are the same. Question 2: Describe how you might change the speed of a wave moving through a slinky. Change the medium In this case, change the tension in the slinky Question 3: What happens to the wavelength of the waves as the frequency of oscillations decreases? The wavelength increases Wave Equation PS Check 1.10s m/s 3.a..29m/s b..21s 4.6.0x10 -7 m 5.a. 545 meters and 188 meters b. 3.4m and 2.8m 6.a. 1500m/s b. 1.00x10 -6 s c. Same as b. Agenda 11/3/15 Warm-Up Activities Check Homework Nspire Homework check Demo on a String What do you Hear Demo Take out a half sheet of paper. Here is what will happen: You will walk one at a time from one end of the room to the other. What do you expect you will hear? After you have walked across the room: Record exactly what you heard Why did you hear this? Learning Target #7: I can apply the principle of superposition and explain what causes interference patterns in wave. Constructive Interference When the crest of one wave overlaps with the crest of another wave Results in increased amplitude Just add up the two waves Constructive Interference Label nodes and antinodes When are the waves in phase? 0 phase shift When are the waves out of phase? 180 phase shift Destructive Interference When the crest of one wave overlaps with the trough of another wave Results in decreased amplitude Just add up the two waves Practice More practice Complete Wave Interference PS Demo on a String!! Agenda 11/4/15 Standing Waves Finish up from yesterday Complete SW PS Finish by end of 1 st Period Review for Unit QUEST Complete Review Guide QUEST: TOMORROW Standing Waves Waves that appear as if the wave is not moving. Standing waves are said to be perfectly out of phase. The incident wave and the reflected wave are exact opposites of each other. Standing Waves Notice: For a standing wave to occur, the wavelength must be related to the string length Standing Waves HarmonicWavelengthFrequency 1 st Ex: 2 nd Ex: 3 rd Ex: 4th Ex: Length of the string is: 1m Complete Standing Wave PS Agenda 11/5/15 Last Minute Questions on Review Guide QUEST