chapter 11.3. reflection reflection occurs when an object or a wave hits a surface through which it...
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![Page 1: Chapter 11.3. Reflection Reflection occurs when an object or a wave hits a surface through which it cannot pass, and it bounces back Examples: Shouting](https://reader035.vdocuments.mx/reader035/viewer/2022062313/56649cec5503460f949b8a25/html5/thumbnails/1.jpg)
Chapter 11.3
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ReflectionReflection occurs when an object or a wave
hits a surface through which it cannot pass, and it bounces backExamples:
Shouting in an empty gym Looking in a mirror
The law of reflection: the angle of incidence equals the angle of reflection
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The Law of Reflection
• Angle of reflection= Angle of incidence
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Free end and Fixed end reflection
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Refraction• The bending of waves
due to changes in speed is called refraction
• Refraction occurs when a wave enters a new medium at angle, one side of the wave changes speed before the other side, causing the wave to bend
• Bending occurs because the two sides of the wave are traveling at different speeds
• Examples:– Seeing a rainbow– Trying to grab an
object underwater
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What are the two mediums the straw has entered?
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DiffractionDiffraction occurs when a wave bends around
a barrier or passes through an opening in a barrier, it bends and spreads out
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Interference
Two waves can overlap when they meetInterference is the interaction between waves
when they meetThere are two types of Interference
1. Constructive Interference2. Destructive Interference
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Constructive Interference• Constructive Interference
occurs when waves combine to make a wave with a larger amplitude
• When crests from each wave meet, constructive interference makes a higher crest in the area of overlap– The amplitude of this
crest is the sum of the amplitude of the two original crests
• After the waves pass through each other they continue on as if they had never met
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Destructive Interference• Destructive Interference
occurs when two waves combine to make a wave with a smaller amplitude
• Can be thought of as subtracting energies
• Destructive interference occurs when the crest of one wave overlaps the trough of another wave– If the crest has a larger
amplitude than the trough, the crest wins and part of it remains
– If the original trough has the larger amplitude the result is a trough
– If the original waves have equal amplitudes then the crest and trough completely cancel out
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Standing Waves• Occurs when an
incoming wave and reflected wave have just the right frequency, and they produce a wave that appears to be standing still
• A standing wave appears to be standing in one place, but in reality it is really two waves interfering as they pass
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Nodes and AntinodesNodes are points of
zero amplitude produced by destructive interference of standing wavesNodes are always
evenly spaced along a wave
Antinodes are points of maximum amplitude on a standing wave created by constructive interferenceAntinodes are also the
points of maximum energy on the wave
Antinodes occur halfway between nodes
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Resonance• Most objects have at
least one natural frequency of vibration
• If a nearby object vibrates at the same frequency it can cause resonance
• Resonance is an increase in the amplitude of a vibration that occurs when external vibrations match an object’s natural frequency
• Resonance can be useful– Example: musical
instruments use resonance to produce stronger, clearer sounds
• Resonance can be harmful– Earthquakes (Mexico
City Earthquake of 1985)