2.5 - Wave Motion and Sound Flashcards
What is the formula for time period?
T = 1/f
where
T = Time period
f = frequency
What is the Doppler effect?
The Dopper effect (or the Doppler shift) is the change in frequency of a wave (or other periodic event) for an observer moving relative to its source
What is the type of wave that moves parallel direction?
Longitudinal or compressed wave
'’Wave in which particles of the medium move in a direction parallel to the direction which the wave moves’’
Give an example of a Longitudinal wave?
Sound wave
What is the wave in which vibrations are perpendicular to the direciton of wave travel?
examples?
Transverse wave
'’Wave moves in a direction perpendicular to the direction which the wave moves’’
energy transported left to right and particles up and down
Transverse waves = light, radio waves, microwaves
In terms of the Doppler effect, what happens when the source moves toward and away from observer?
If the source is moving towards the observer , the observer percieves sound waves reaching him or her at a more frequent rate (high pitch)
if the source is moving away from the observer, the observer percieves sound waves reaching him or her at a less frequent rate (low pitch)
If the source is moving towards the observer , the observer percieves sound waves reaching him or her at _______________________
if the source is moving away from the observer, the observer percieves sound waves reaching him or her at ___________________
If the source is moving towards the observer , the observer percieves sound waves reaching him or her at a more frequent rate (high pitch)
if the source is moving away from the observer, the observer percieves sound waves reaching him or her at a less frequent rate (low pitch)
Where is the position of the nodes and antinodes on a wave graph?
Antinodes at the top of each wave (A)
Nodes are at the 0 point, along the axis
What would be positioned at the fixed end of a wave that is reflected?
(node or antinode)
node
(thus has to be antinode at the open end)
Superposition of waves
What happens to a constructive wave?
When two peaks coincide, constructive waves occur that are at the same frequency will increase the amplitude
Superposition of waves
What happens to a destructive wave?
When at the same frequency and a trough coincides with a peak
destrucive interference occurss (noise cancelling)
What is a standing wave?
Standing or stationary wave is a wavve in which each point of the wave has an associated amplitude.
The locations at which the amplitude is minimum are called nodes and the locations where the amplitude is maximum are called antinodes
What is the speed of sound in each of the following:
air @ 0^C =
air @ 20^C =
steel =
What is the speed of sound in each of the following:
air @ 0^C = 331 m/s
air @ 20^C = 344 m/s
steel = 5790 m/s
What does the amplitude of a wave correspond to?
The greater the amplitude of a wave then the more energy it is carrying
(energy)
What is timbre?
All objects have a natural frequency and the quality of this and musical instruments is defined as timbre
Sound quality (tone) depends on
the mix of harmonics
Sound waves are transferred through the air by:
a) electromagnetic waves
b) alternate low and high pressure air
b) alternate low and high pressure air
What is meant by the term resonance?
Resonance describes when a vibrating or external force drives another system to oscillate with greater amplitude at a specific pefererntial frequency.
Frequencies at which the response amplitude is a relative maximum are known as the system’s resonant frequencies or natural frequencies
What is meant by beat frequency?
Suppose we tune two strings of a guitar to vibrate almost, but not quite, the same frequency.
Plucked simultaneously, the volume of the sound produced by them appears to rise and fall continuously.
This rise and fall has a fixed frequency called the beat frequency
What is happening is that the sound waves prodcued by the two guitar strings interfere and our ears detect the variation of the resultant intensity. Maximum intensity is heard when the waves add together (interfere constructively) and minimum intensity is heard when the waves cancel each other out (interfere destructively)
In terms of a sound wave
The pitch corresponds to the ________
the loudness corresponds to the ______
The pitch corresponds to the frequency
the loudness corresponds to the amplitude
which is high vs low frequency
Rafeifraction is related to which type of wave?
Compression (longitudinal) wave
What is the speed of sound in air at 0 ^C?
331 m/s
Doubling of wavelengths results in ______________________
halving the frequency, but wave speed does not change
A high pitch sound corresponds to a _____frequency and a low pitch sound corresponds to a _______ frequency
A high pitch sound corresponds to a high frequency and a low pitch sound corresponds to a low frequency
When two waves interfere, the resulting displacement of the medium at any location is
the algebraic sum of the displacements of the individual waves at that same location
When 2 waves of the same phase coincide, is it?
a) constructive
b) destructive
interference
a) constructive
What is a standing wave?
Interference between a wave and its own rebound reflection creates a ‘standing wave’
