Properties of mechanical waves Flashcards
Amplitude
amplitude is the magnitude of the maximum oscillation
Compression
compression a point in the medium of a longitudinal wave where pressure is maximum
Crest
crest a point in the medium of a transverse wave where particles have maximum positive displacement
Frequency
frequency the number of wave cycles completed per unit of time
Longitudinal (compression wave)
longitudinal (compression) wave a wave in which the oscillations are parallel to the direction of wave travel and energy transmission
Mechanical wave
mechanical wave a wave which requires a material medium
Medium
medium the physical substance through which a wave propagates
Period
period the time taken to complete one wave cycle
Rarefaction
rarefaction a point in the medium of a longitudinal wave where pressure is minimum
Tranverse wave
transverse wave a wave in which the oscillations are perpendicular to the direction of wave travel and energy transmission
Trough
trough a point in the medium of a transverse wave where particles have maximum negative displacement
Wave
wave the transmission of energy via oscillations from one location to another without the net transfer of matter
Wave cycle
wave cycle the process of a wave completing one full oscillation, ending up in a final configuration identical to the initial configuration
Wavelength
wavelength the distance between two identical points in a wave
Wavespeed
wave speed the speed at which a wave propagates through a medium
Doppler effect
Doppler effect the detected frequency change due to the relative motion between a wave source and detector
Antinode
antinode a point where constructive interference consistently occurs
Coherance
Coherance is two wave sources that create the same frequency within a medium
Interference
interference superposition creating a larger (constructive) or smaller (destructive) resultant wave
Node
node a point where destructive interference consistently occurs
Path difference
path difference the difference in length between paths from two different wave sources to the same endpoint
Superposition
superposition the addition of overlapping waves in the same medium
Forced oscillation
forced oscillation the oscillation caused by an external driving force
Natural freqnecy/ resonance frequency
natural frequency the frequency of oscillations within an object when not driven by an external periodic force
Resonance
resonance the process by which the amplitude of an oscillation increases when forced oscillations match the natural frequency
Fundamental frequency
fundamental frequency the lowest frequency of a standing wave in a given medium
Harmonic
harmonic a standing wave with a frequency equal to an integer multiple of the fundamental frequency
Standing wave/stationary wave
standing wave a wave for which the positions of maximum amplitude (antinodes) and zero amplitude (nodes) are constant; a superposition of two waves travelling in opposite directions with the same frequency and amplitude
Travelling wave
travelling wave a wave for which the crests and troughs (or compression and rarefaction) travel in the direction of wave propagation
Aperature
aperture a hole, gap, or slit through which a wave travels
Diffraction
diffraction the spread of a wave around an obstacle or through an aperture
Example of a tranverse wave diagram
Example of a longitudal wave diagram
What are the propertities of waves?
–> Amplitude (A)
–> Wavelength (λ)
–> Period (T)
–> Frequency (f)
What is the formula that shows the relationship between frecunecy and the period?
f=1/T
Where f=frequency
T=Period
Graphing Wave representation: Displacement-distance and Displacement-time graph
What are the two wave equations?
In reference to resonance what occurs at a “fixed end”
Fixed ends reflect and invert the wave.
In reference to resonance what happens to a “free end”
Free ends reflect but do not invert the wave.
What happens to an object if driven by its natural frequency?
An object or system will resonate (amplitude increase) if it is driven at its natural frequency.
What is the effect of resonance on an object?
Resonance greatly increases the magnitude of oscillation in an object or system. Which can shatter a glass souly through intense bivarations due to a singer producing sound waves at a natrual frequency.
What occurs with standing waves with 2 fixed ends?
When two waves with the same amplitude and frequency travel in opposite directions, an interference pattern forms from their superposition.
A superposotion is where two or more waves of the same type cross at some point, the resultant displacement at that point is equal to the sum of the displacements due to each individual wave.
Superposition
Two or more waves of the same type cross at some point, the resultant displacement at that point is equal to the sum of the displacements due to each individual wave.
What is the formula for strings with two fixed ends
What must a standing wave with two fixed ends have?
A standing wave must have two fixed end nodes as the wave lengths correspond
What occurs with a standing wave with one fixed end
Standing waves with one fixed end and one free end are again formed by the superposition of two identical waves travelling in opposite directions. They always have a node at the fixed end and an antinode at the free end.
Harmonics regarding standing waves with one fixed end
On a string with one fixed end, standing waves are constrained by the fact that there must be a node at the fixed end and an antinode at the free end. Therefore in order for this to occur n (the harmonic number) must be an odd integer.
For strings with one fixed end, the wavelength and frequency of standing waves can be calculated by the following formula:
Standing waves 1 fixed end vs 2 fixed end
Standing waves on a string with two fixed ends form so that the length of the string is an integer multiple of half of the wavelength. Standing waves on a string with one fixed end and one free end form so that the length of the string is an odd multiple of one quarter of the wavelength.
Examples of diffraction
Diffraction occurs every time a wave interacts with the edge of an obstacle. This is shown through ripples in water where diffraction can be seen through the created pattern.
When analyzing diffraction it is found there certain porporotions and dependants. What are those?
