1. Answer the following…
17. What happens to the amplitude of a pulse as it travels down the slinky and back?
18. What happens to the speed of a pulse as it travels down the slinky and back?
19. What do you observe about a pulse after it reaches the end of the medium that is fixed in place?
20. What do you observe about a pulse after it reaches the end of a medium that is free to move?
21. What would happen to a wave pulse on a spring if it encountered a new spring with different characteristics?

2. When a pulse encounters a medium boundary 2 things happen…
Reflection
Some energy of the wave pulse is bounced back into the original medium.
Transmission
Some energy of the wave pulse passes through the boundary into the new medium

3. Fixed End Reflection
At a fixed boundary, waves are inverted as they are reflected.

4. Free End Reflection
At a free boundary, waves are reflected on the same side of equilibrium

5. Transmission If the wave pulse goes from…
Low density  High density medium
Reflected pulse is inverted
Transmitted pulse is upright
High density  Low density medium
Reflected pulse is upright
Transmitted pulse is upright

6. What happens when wave pulses move through a medium at the same time?

7. What happens when wave pulses move through a medium at the same time?
When this occurs, waves are said to experience interference

8. Wave Interference is described by the Superposition Principle…

9. Wave Interference is described by the Superposition Principle…
Wave pulses (energy) pass through each other completely unaffected

10. Wave Interference is described by the Superposition Principle…
Wave pulses (energy) pass through each other completely unaffected
The medium will be displaced an amount equal to the vector sum of what the waves would have done individually
This results in two different types of interference: constructive and destructive

11. Constructive Interference
Pulses must meet when on the same side of equilibrium.
The resultant displacement of the medium greater than both originals

12. Destructive Interference
Pulses must meet when on opposite sides of equilibrium.
The resultant displacement of the medium is less than at least one original

13. http://www. animations. physics. unsw. edu

14. Standing Waves
An interference pattern that results when two waves of the same frequency, wavelength, and amplitude travel in opposite directions and interfere.

15. Standing wave parts
Node – point that maintains zero displacement, complete destructive interference
Antinode – point at which largest displacement occurs, constructive interference

16. Standing waves
Only specific frequency-wavelength combinations will produce standing wave patterns in a given medium.

17. From the standing wave lab…
Frequency and wavelength are inversely proportional for a wave in a given medium.
v = f
v – velocity of wave (constant for a given medium)
f – frequency of the wave, # of waves per second
 – wavelength, how far the wave travels in a single period
Remember that f = 1/T, so the equation above could also be written as 𝒗= 𝝀 𝑻