# Phys II Exam I

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 Author: mse263 ID: 130302 Filename: Phys II Exam I Updated: 2012-03-01 08:10:17 Tags: duh Folders: Description: fuck fuck Show Answers:

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1. The speed at which waves move through a medium is
dependent:
upon the properties of the medium
2. wavelength of the harmonic is dependent upon the:
length of the string and the harmonic number
3. pulse
a single disturbance moving through a medium from one location to another location
4. a wave transports its energy without transporting
matter
5. transverse wave
a wave in which particles of the medium move in a direction perpendicular to the direction that the wave moves; characterized by particle motion being perpendicular to wave motion
6. longitudinal wave
a wave in which particles of the medium move in a direction parallel to the direction that the wave moves
7. waves traveling through the bulk of a fluid (such as a liquid or a gas) are always:
longitudinal waves
8. mechanical wave
a wave that is not capable of transmitting its energy through a vacuum; they require a medium in order to transport their energy from one location to another (eg. sound wave)
9. wavelength
is simply the length of one complete wave cycle

-can be measured as the distance from crest to crest or from trough to trough
10. compression
a point on a medium through which a longitudinal wave is traveling that has the maximum density; a region where the medium is pressed together in a small amount of space
11. rarefaction
a point on a medium through which a longitudinal wave is traveling that has the minimum density
12. frequency
refers to how often the particles of the medium vibrate when a wave passes through the medium (Hz, cycles/second)
13. period
the time for a particle on a medium to make one complete vibrational cycle
14. speed
the distance traveled by a given point on the wave (such as a crest) in a given period of time
15. as the frequency of a wave increases, the period of the wave ___________
decreases; period is the reciprocal of the frequency; so as f increases, 1/f decreases
16. Stuff from Problem Sheet 6 (but like not really)
17. the ________________ determines the focal length of a lens
shape of the lens and the density of the material from which its made
18. diverging lens
19. The amount of energy carried by a wave is related to the_________ of the wave
amplitude; basically the more energy put in/work done on an wave (?) results in higher amplitudes of the wave (if you think about it literally like moving a string); putting a lot of energy into a transverse pulse will not affect the wavelength, frequency or speed of the pulse, only the amplitude
20. variables that affect the speed at which a wave travels through a medium:
only tension: the speed of the waves was significantly higher at higher tension

• -the speed of a wave is not dependent upon properties of the wave, rather, it's dependent upon the properties of the medium (eg. tension of the rope)
• -so remember, things like amplitude (aka energy), freq., or wavelength DO NOT affect the speed of a wave
21. speed =
velocity * wavelength
22. incident pulse
If a pulse is introduced at the left end of a rope, it will travel through the rope towards the right end of the medium (where there's a fixed end); this pulse is called the 'incident' because it's incident towards the boundary
23. fixed end v. free end reflection
• -if a wave is directed toward a fixed end it will be reflected inverted; same freq., same wavelength but smaller amplitude (some energy is lost to the 'fixed end'
• -if a wave is sent to a free end it will be reflected in the same orientation that it was originally sent in (so not inverted)

• -The transmitted pulse (in the more dense medium) is traveling slower than the reflected pulse (in the less dense medium)
• -The transmitted pulse (in the more dense medium) has a smaller wavelength than the reflected pulse (in the less dense medium)
• -The speed and the wavelength of the reflected pulse are the same as the speed and the wavelength of the incident pulse.
24. Pulse Transmission Across a Boundary: Less to More Dense
• -transmitted pulses can never be inverted
• -since the particles in this medium are originally at rest, any change in their state of motion would be in the same direction as the displacement of the particles of the incident pulse
25. Pulse Transmission Across a Boundary: More to Less Dense
• -The transmitted pulse (in the less dense medium) is traveling faster than the reflected pulse (in the more dense medium)
• -The transmitted pulse (in the less dense medium) has a larger wavelength than the reflected pulse (in the more dense medium)
• -The speed and the wavelength of the reflected pulse are the same as the speed and the wavelength of the incident pulse.
26. reflection v. refraction
-reflection: a change in direction of waves when they bounce off a barrier

• -refraction: a change in the direction of waves as they pass from one medium to another.
• -Refraction = the bending of the path of the waves
• -accompanied by a change in speed & wavelength of the waves
27. diffraction
involves a change in direction of waves as they pass through an opening or around a barrier in their path

• -amount of diffraction (the sharpness of the bending) increases with increasing wavelength and decreases with decreasing wavelength
• *when the wavelength of the waves is smaller than the obstacle, no noticeable diffraction occurs
28. wave interference
the phenomenon that occurs when two waves meet while traveling along the same medium
29. constructive interference
a type of interference that occurs at any location along the medium where the two interfering waves have a displacement in the same direction (so if to inverted waves are both displaced in the inverted direction, or the reverse)
30. Destructive interference
a type of interference that occurs at any location along the medium where the two interfering waves have a displacement in the opposite direction
31. for an OPEN ended column (on both sides):

for an OPEN end CLOSED end column (one on e/a side):
• the nodes correspond to the harmonic:
• -1st harmonic has 1 node, 2nd has 2, etc etc

• for an OPEN end/CLOSED end column (one on e/a side): odd numbers
• harmonic 1: 1 node
• harmonic 3: 2 node
• harmonic 5: 3 node
• harmonic 7: 4 node
• harmonic 9: 5 node
32. also for open end: remember this pattern
• harmonic 1: L = 1/2 λ
• harmonic 2: L = 2/2(1) λ
• harmonic 3: L = 3/2 λ
• harmonic 4: L = 4/2 λ
• harmonic 5: L = 5/2 λ

JUST PUT ALL OF THE HARMONIC #'S OVER 2 AND MULT BY WAVELENGTH L = _/2 λ
33. also for open-CLOSED end: remember this pattern
• harmonic 1: L = 1/4 λ
• harmonic 3: L = 3/4 λ
• harmonic 5: L = 5/4 λ
• harmonic 7: L = 7/4 λ
• harmonic 9: L = 9/4 λ

JUST PUT ALL OF THE HARMONIC #'S OVER 4 AND MULT BY WAVELENGTH L = _/4 λ

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