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.