Slinky Wave Review
Reflection
• Waves bouncing off barriers
– Fixed End Reflection
– Free End Reflection
– Speed of reflected wave is same as incident wave
Reflection
Energy bouncing off a barrier
•
Review of Part II
–
What happens to the pulse amplitude on FIXED END
reflection?
• Bounces Back Upside down
–
What happens to the pulse amplitude on FREE END
reflection?
• Bounces Back Right Side Up
–
What happens to the speed of the reflected wave compared
to the speed of the incident wave?
• Speed is the same
• Medium Does not Change
Interference
2 or more waves meeting
• Review of Part III
– Below are two waves. Sketch what happens
when they meet?
– What kind of interference is this?
• Constructive Interference
– What happens to the energy when the waves
overlap? How do we know?
• Energy Increases
• Larger Amplitude
Interference
2 or more waves meeting
• Review of Part III (cont.)
– Below are two waves. Sketch what happens
when they meet?
– What kind of interference is this?
• Destructive Interference
– What happens to the energy when the waves
overlap? How do we know?
• Energy Decreases
• Smaller or No Amplitude
Interference
2 or more waves meeting
• Review of Part III (cont.)
– Below are two waves. Sketch what happens
AFTER they meet?
– Do the waves bounce off of each other?
• Nope
• Pass Through each other
– Do the waves change speed? Why?
• Nope
• Medium has not changed
Interference
• When 2 or more waves meet
–Superpostion-Adding or Subtracting
the amplitudes
Interference
• Special Case of Interference
– Periodic Waves- waves generated at a constant
frequency
Interference
• Special Case of Interference
– Periodic Waves- waves generated at a constant
frequency
– This means we will get constructive and
destructive interference continually!
Interference
• Special Case of Interference
– Periodic Waves- waves generated at a constant
frequency
– This means we will get constructive and
destructive interference continually!
– This is called a ‘Standing Wave Pattern’
Refraction
• When a wave enters a new medium
Refraction
• When a wave enters a new medium
• Since the wave enters a new medium, what
has to happen?
Refraction
• When a wave enters a new medium
• Since the wave enters a new medium, what
has to happen?
SPEED CHANGES!
Refraction
• What happens to the energy at the junction?
Refraction
• What happens to the energy at the junction?
It Splits
Some gets transmitted (continues to move into
the new medium) and some gets reflected back
(free end or fixed end)
Refraction
• Send a pulse from a light coil to a
heavy coil
Incident wave
Refraction
• Send a pulse from a light coil to a heavy coil
Before
Transmitted wave
After
Reflected Wave
Acts like a FIXED END
Refraction
• Send a pulse from a heavy coil to a light coil
Incident wave
Refraction
• Send a pulse from a heavy coil to a light coil
Reflected
wave
Transmitted wave
Acts like a FREE END
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