Thurs. Mar. 6 Do Now: Circle the type of wave that needs a medium through which to travel: Mechanical or Electromagnetic  A wave has a wavelength of 8m and a frequency of 4 Hz. What is the wave’s speed? ________  Look at the two waves below. Circle the one with the greatest wavelength.  

Students will be able to – Learning Goals: Students will be able to – Explain the 4 ways in which waves interact Illustrate the 4 types of wave interactions and provide examples of each

Activity: You are going to investigate the different ways that waves interact with one another. Each person needs to fill out a chart based about the 4 types of interactions: Refraction Reflection Diffraction Absorption

Reflection When waves strike an object and bounce off of it Examples Mirror Echos

Refraction A wave travels from one medium to another so it changes speed and bends Examples Things under water Prisms bending white light into colors

Diffraction Waves bend around a barrier Examples Waves bend around rocks in the ocean

Absorption Waves can be absorbed as they pass through objects Amplitude gets smaller as it passes through material Example: Sponge absorbing water waves Sunglasses have dark light that absorbs light

Activity Continued: Once your chart is filled in you need to find your group and receive your assigned interaction Your group will make a poster about the interaction including Definition Illustration Examples

Do Now: What do you think happens when two waves bump into each other?   Do you think a wave can stand still?

Students will be able to – Learning Goals: Students will be able to – Define constructive and destructive interference Classify standing waves, interference and wave behaviors in examples

Label amplitude:

Label the Wave Behavior:

Label the Wave Behavior: C: ____________________ D: ____________________

Wave Interference Two or more waves overlap and combine to form a new wave

Examples of Interference: http://id.mind.net/~zona/mstm/physics/wav es/interference/waveInterference2/WaveInterf erence2.html

Constructive Interference When does it happen? When waves are on the same side and add together Same side = in phase Crest adds to another crest What happens to the amplitude? Becomes larger

Destructive Interference When does it happen? Waves on opposite sides add together Opposite sides = out of phase Crest and trough meet What happens to the amplitude? Becomes smaller

Interference Constructive Destructive

Example – Sound Interference:   The sound from two speakers meeting and amplifying the sound is an example of _______________________ interference. The sound from two speakers meeting and canceling out is an example of _________________________ interference.

Example – Light Interference: The light from two sources meeting and amplifying the light is an example of ___________________ interference.   The light from two sources meeting and canceling each other out is an example of __________________ interference.

Standing Waves: Occurs when a wave is trapped in one spot between boundaries

Practice on Your Own: Complete the practice portion of today’s packet with a partner

Answers: The bending of a wave caused by a change in speed when moving from one medium to another. The reason that objects under water appear to be closer to the surface than they really are. The bending of a wave as it moves around an obstacle.

Answers Continued: What happens to sound waves that causes us to hear an echo? A light or sound wave being bounced back from a surface. What happens when water waves bend around rocks in the ocean.

Answers Continued: What happens to sound waves in a concert hall that makes some areas appear louder and some areas are “dead spaces”? When trying to spear a fish in water, a person needs to take into account the way light bends as it moves from water into air, which is called— What happens to light waves reflecting off of a layer of oil that creates the different colors?

Answers Continued: Two waves reflect and interfere so perfectly that crests meet crests and troughs meet troughs. What happens to light waves that allows us to see ourselves in a mirror? Two or more waves overlap and combine to form a new wave.

Create Your Own Example: Step 1: Draw a graph of a wave Step 2: Draw a second wave that differs from the first Step 3: Draw the graph of the wave that would result if you put wave 1 and wave 2 together

Do Now Get a piece of colored paper Write a thank you note to a teacher, parent, family-member, or anyone who has helped you be successful in your education and reach your goals

Words Have Multiple Meanings Date Leaves Engaged Point Right Resonance

Resonance Richness or significance, especially in producing a strong emotion Physical Science Book: An occurrence in which the natural frequency of a system is exactly in tune with a force applied to a system

What the heck does that mean??? Lets start with natural frequency Describes how an object vibrates If you pluck a guitar string 10 times and measure the frequency – the frequency of vibration will always be the same Tuning forks each have a natural frequency in which they vibrate at

Tuning a Guitar Musical instruments work by adjusting the natural frequency of vibrating strings or air to match musical notes Tuning a guitar changes the natural frequency of a string by changing its tension

Back to Resonance When the natural frequency matches the force applied causing a wave Results in the amplitude of the oscillation growing Example: Swing Small pushes add up to a large amplitude of motion By applying small pushes at a frequency matched to the natural frequency we create a large motion Repeated pushes and natural motion creates resonance

Video Example https://www.youtube.com/watch?v=nL4xv4UqgHE

Activity to Investigate Work in groups of 2-3 One person from each group needs to come up front and get the materials: Graduated cylinder Tuning fork Mallet Beaker of water DO NOT MAKE A MESS! Act like the YOUNG ADULTS I know you can be 

Do Now: What is the unit for frequency? As wavelength of a wave increases, what happens to the speed of the wave? What is the equation for the speed of a wave?

Objectives: Learning Intentions – Success Criteria – Students will be able to explain and show understanding of material from the first half of the unit on the assessment Success Criteria – We will know we are successful when we can accurately demonstrate knowledge from the first half of the unit on the assessment

Questions?? Topics covered on quiz: What is a wave? 6 types of waves Mechanical vs. Electromagnetic waves Transverse vs. Longitudinal waves Parts of a wave: crest, trough, node, amplitude, wavelength Calculating speed of a wave

When finished… Turn in quiz on the stool up front Pick up a reading from the text Read and underline important points Make a Frayer model of one of the key vocabulary words from the reading