lesson 13 review section
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1. Complete Warm-Up for April 9th. Work with your shoulder partner first. Then swap and compare answers with the rest of your team.
2. The team with the most correct answers are “King/Queen for the day” and the rolling chairs.
3. Get your journal ready. Add one page of guided notes to the next available page.
4. Time Limit: 8 minutes
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S8P5: Students will explore the wave nature of sound and electromagnetic radiation.
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a. Identify the characteristics of electromagnetic and mechanical waves.
b. Describe how the behavior of light waves is manipulated causing reflection, refraction diffraction, and absorption).
c. Explain how the human eye sees objects and colors in terms of wavelengths.
d. Describe how the behavior of waves is affected by medium (such as air, water, solids).
e. Relate the properties of sound to everyday experiences.
f. Diagram the parts of the wave and explain how the parts are affected by changes in amplitude and pitch.
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How can light and sound be used as tools? D
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What happens when a waves encounters a boundary (a new medium)?
3. Transmission – to pass through
1. Absorption
2. Reflection
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Energy in wave is transformed into adifferent form of energy, usually thermal energy.
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1.Reflection
2.Refraction
3.Diffraction
4.Interference
5.Polarization
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occurs when a wave strikes an object and bounces off
occurs with all types of waves obeys the Law of Reflection – the
angle of incidence is equal to the angle of reflection D
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When a wave enters a new medium at an angle, one side of the wave changes speed before the other side, causing the wave to bend.
• amount of bending depends on the speed of light in both materials
• the greater the difference between the speeds of light in the two media, the more the light is bent
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REFRACTION IN NATURE
Wave speed depends on the medium
Click on picture for internet animation
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bending of light around a barrier occurs with all types of waves
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Diffraction• A wave spreading
• A wave passes a barrier or moves through a hole in a barrier…• it bends and spreads out
• ex: a harbor
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D. Goldsberry 4/9/12
DIFFRACTION
• familiar examples: sound waves (speakers in a room) and water waves (breaker opening in harbors)
• the amount of diffraction increases with increasing λ
when a wave bends around an edge or spreads through an opening
White light can be separated into the visible spectrum colors by bending the light with refraction or diffraction
red light is bent the least violet light is bent the most
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• caused when light waves overlap each other
a) constructive – interact to build up wave
b) destructive – interact to reduce wave D
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INTERFERENCEwhen 2 or more waves meet while traveling in the same medium (overlapping waves)
the NET displacement (amplitude) is the sum of the amplitude of the waves
Constructive or destructive interference
Creates standing waves & beats
Interference• the result of two or more sound• waves overlapping
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Interference• Waves combining• Constructive interference
• Waves add together to make a larger amplitude
+ =
+
=
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CONSTRUCTIVE INTERFERENCE
larger displacement (larger amplitude)
crest overlaps crest
or tough overlaps trough
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CONSTRUCTIVE INTERFERENCE
Resonance
When an object vibration at a particular frequency
Seen in musical instruments, especially strings
Sympathetic resonanceWhen one vibrating object induces a vibration in another object
Soldiers do not walk in formation across bridges
Tacoma Narrows Bridge
Interference (cont.)• Destructive interference
• Waves add together to make a smaller amplitude
+ =
+
=
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DESTRUCTIVE INTERFERENCEsmaller displacement (smaller amplitude)
crest cancels trough
crest overlaps trough
displacement/ amplitude is reduced
Different sounds that you hear include (A) noise, (B) pure tones, and (C) musical notes.
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In music interference creates “beats” (changes in loudness & softness)
BEATS: INTERFERENCE
Wave 1 (red) and Wave 2 (blue)
combine to form beat pattern (in green)
High amplitude = LOUDLow amplitude = soft
Overlapping waves of different f (frequencies)
A polarizing filter acts as though it has tiny slits in one direction.
Only some of the light (vibrating in the same way as the slit) can pass through a polarized filter
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