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26 Cards in this Set
- Front
- Back
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List the 5 characteristics of a wave
List name, description and units |
Frequency (f): Cycles per second (1/s). Measured in hertz (Hz)
Period (T): How long it takes point to make one up-down roundtrip. Measured in seconds (s) Amplitude (A): Maximum distance from where resting point, to highest peak, or lowest trough. Measured in meters (m), or a derivative of a meter. Wavelength (λ): Distance from crest to crest, or trough to trough. Measured in meters (m), or a derivative of a meter. Wavespeed (v): Speed of the wave. Measured in meters per second (m/s). |
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Define:
Transverse Wave |
Disturbance is traveling perpendicular to direction of travel.
e.g. Rope attached to a wall. A point on the rope is moving vertically, while the wave moves horizontally. |
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Define:
Wave |
A disturbance of some kind that travels from one point to another.
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Frequency and Period are...
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...inversely related.
Period = 1/Frequency T = 1/f Frequency = 1/Period f = 1/T |
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List the 2 rules for waves
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1) Velocity does not depend on frequency. It depends on the medium.
2) When a wave passes into a new medium, frequency does not change but velocity will change. |
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Define:
Medium |
What a wave uses to travel from point A to point B.
e.g. Rope, water, air |
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Define:
Interference |
When two or more waves combine.
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Define:
Constructive Interference Resulting amplitude will be... |
When two or more combining waves are "in phase".
Crest meets crest, trough meets trough. Amplitude = A_1 + A_2 |
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Define:
Destructive Interference Resulting amplitude will be... |
When two waves are (exactly) out of phase.
Crest meets trough. Amplitude = |A_1 - A_2| |
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During Interference between two waves, the amplitude of the resulting wave will always be...
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...between the difference and the sum of the amplitudes of the two waves.
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Reflection and Transmission:
If the first wave hits something "harder", the reflected pulse will be _____ compared to the original. |
upside-down
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Reflection and Transmission:
Transmitted waves are always positioned _____ _____ as the original. |
the same
i.e. If the original wave was positioned upwards before it passes into the new medium (exa = a rope), then the transmitted wave will be upwards also. The *reflected* wave may be upside-down. |
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Define:
Node |
Place of no displacement on a standing wave.
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Define:
Antinode |
Place of maximal displacement on a standing wave.
This corresponds to the crests and troughs. |
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Standing Waves:
Nodes and antinodes are always _____ _____. |
evenly spaced.
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Define:
Overtone |
How many past the fundamental we are.
e.g. The 6'th overtone is the 7'th harmonic. |
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In general:
The overtone number is always _____ than the harmonic number. The harmonic number is always _____ than the overtone number. |
...lower...
e.g. The 6'th overtone is the 7'th harmonic. ...higher... e.g. the 4'th harmonic is the 3'rd overtone |
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Define:
Standing wave |
Formed by two oppositely directed traveling waves on the same string.
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Standing Waves:
The first harmonic is referred to as the _____. |
Fundamental
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Standing Waves:
Any frequency must be a _____ of the fundamental frequency. |
multiple
e.g. if f(1) = 3 Hz, f(2) could *not* be 8 Hz. |
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Define:
Longitudinal Wave |
Molecules bound in the *same direction* as the wave motion.
i.e. parallel e.g. Sound waves |
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The velocity that a sound travels through a gas (e.g. air) is...
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...340 m/s
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Intensity Level:
In "I" is multiplied by 10, you... If "I" is divided by 10 you... |
...*add* 10 to the decibel level.
...*subtract* 10 from the decibel level. |
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Describe:
The Doppler Effect |
If there is relative motion between the source of a sound and the detector (e.g. your ear), then the frequency detected does not equal the frequency emitted by the source.
e.g. You're standing stationary on a sidewalk; the pitch in sound you hear from the siren of an ambulance will increase as it moves toward you, and decrease as it moves away. |
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Two concepts to remember for Doppler Effect type problems:
Moving toward the source will... Moving away from the source will... |
...INCREASE the frequency.
...DECREASE the frequency. |
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I_o (I sub zero) is known as...
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...the Threshold of Hearing.
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