Bellwork: Turn in your homework from last night into the drawer in the front of the room. Any homework turned in after the end of bellwork will be considered late and you will complete an alternate assignment at Saturday School T/F Waves carry matter as they travel from one place to another Not all waves move energy Sound waves can travel where there is no matter All waves are the same shape and size Waves that carry more energy cause particles to move a greater distance
What are waves? A disturbance that travels through matter or space They transfer energy from place to place but do not transfer matter.
What are mechanical waves?
What do waves travel through Medium – the material through which waves travel. They travel through types of Matter – solids, liquids or gas but not a vacum (empty Space
What are the types of mechanical waves In transverse – the particles move perpendicular to the energy of the wave Example – Water waves
Longitudinal waves In longitudinal – the particles move parallel to the direction the wave travels
Bellwork What are waves? What are mechanical waves What is a medium? What are the types of mechanical waves. Draw and label. Include direction of wave, crest, trough, rarefactions and compressions. Bellwork
What are properties of waves Amplitude - measure of how far particles in the medium are from their normal rest position. As a wave passes, particles vibrate up and down or back and forth in the medium A higher amplitude = higher energy Crests = highest points Troughs = lowest point
What is this wave’s amplitude?
How does amplitude effect energy?
Amplitude Which has a larger amplitude A or B? Why?
2 Wavelength Distance from any point on a wave to the same point later on the wave Ex crest to crest, or trough to trough.
What is this wave’s wavelength?
Frequency – number of crests (or troughs) that pass per unit of time Higher frequency = Higher energy As the frequency increases the wavelength decreases As the frequency decreases, the wavelength increases.
If 1 second passes, what is the frequency of Wave A? Wave B?
Wave speed Different types of waves travel at different speeds. The same type of waves travel at different speeds in different materials. Temperature also affects the speed at which waves travel.
What determines the speed of a wave? Solid – fastest Liquid - in-between Gas – slowest speed
What happens to the wavelength as frequency increases?
Draw a wave on the grid below Draw one with twice the amplitude Draw one with twice the frequency
How do waves interact with matter and each other?
absorption Transfer of energy by a wave into the medium it is in. Amount absorbed depends on the type of wave and the type of medium Darker colors absorb more light energy waves than lighter colors
transmission The passage of light waves through an object
How do waves change direction Reflection Refraction diffraction
Reflection Bouncing of a wave off a surface. All types of waves reflect Light when hit mirror Sound when hit wall Law of reflection: when a wave is reflected from a surface, the angle of reflection is = angle of incidence
Car –label the type of wave interaction
Refraction When a wave changes direction because its speed changes The light waves slow down as they move from air into water
Diffraction The change in direction of a wave when it travels by the edge of an object or through an opening
Lesson 3 – LR1 A. diffraction B. interference C. reflection Which occurs when a wave changes direction because its speed changes? A. diffraction B. interference C. reflection D. refraction
Lesson 3 – LR3 A. the angle of refraction B. the angle of reflection According to the law of reflection, the angle of incidence equals which of these? A. the angle of refraction B. the angle of reflection C. the angle of interference D. the angle of diffraction
Lesson 3 - Now Do you agree or disagree? 5. When light waves strike a mirror, they change direction. 6. Light waves travel at the same speed in all materials.
Exit: What factors affect a waves energy? What is wave energy measured in? What factors affect a waves speed? Draw a longitudinal wave and label the compressions and rarefractions.
Bellwork: You just came home from a day at the beach. You swam in the ocean and stretched out in the sunlight. Your friend brought a radio so you could listen to music. When you arrived home, you heated some pizza in the microwave oven. As you waited for it to cook, you turned on the TV, and then the phone rang. List examples of the waves in the story AND classify as mechanical or electromagnetic
What are electromagnetic waves Electromagnetic – travel through matter and space – Don’t need a medium to travel through - light waves all travel at the same speed because they don’t have a medium.
Wave Animation http://www.glencoe.com/sites/common_assets/science/virtual_labs/E05/E05.html
Bellwork: complete the graphic organizer using the word list below: transverse waves wave properties crest &trough light waves sound waves Frequency Wave speed Wavelength Compression & rarefaction Amplitude Period longitudinal
Bellwork: Copy and complete Word List: transverse longitudinal waves wave properties crest &trough, light waves sound waves, Frequency Wave speed, Wavelength Compression Rarefaction Amplitude Period
What is the difference between a mechanical and electromagnetic wave? What is the difference between a longitudinal and a mechanical wave? (include particle movement and speed in your comparison) What happens to the speed of a wave if it moves from a gas to a solid? Through which media do waves travel the slowest? Fastest? You are floating in a life raft in the ocean. What happens as a wave passes under you? What is the medium the wave is passing through You are screaming for help from your life raft, what medium does the sound wave travel through? A wave has a speed of 2cm/sec. Its frequency is 6Hz. Find the wavelength. Use the formula speed = freq. x wavelength
Exit