Chapter 7.1 Flashcards
What are transverse waves?
- those in which the direction of particle oscillation is perpendicular to the propagation of the wave
- > the particles are oscillating perpendicular to the direction of energy transfer
What are longitudinal waves
- ones in which the particles of the wave oscillate parallel to the direction of propagation
- > so wave particles are oscillating in the direction of energy transfer
- > air molecules oscillate through cycles of compression and rarefaction(decompression) along the direction of motion of the wave
What is a wavelength
-the distance from one maximum crest of the wave to the next
What is frequency
- the number of wavelengths passing a fixed point per second
- >it is measured in hertz or cycles per second
What is period
-the number of cycles per second
What does it mean for two waves to be in phase
- if we consider two waves that have the same frequency, wavelength and amplitude and pass through the same space at the same time
- > the phase difference here is zero
What is the principle of superposition
- it states that when waves interact with each other
- >the displacement of the resultant wave at any point is the sum of the displacements of the two interacting waves
Contrast constructive interference from destructive inteference
In phase waves
- > displacements/amplitudes add up together
- > this is referred to as constructive interference
Out of phase waves
- > displacements counteract each other and the amplitudes are not added but subtracted from each other
- > this is referred to as destructive interference
What is a travelling wave
- if a string at one end is moved up and down
- > a wave will form and travel towards the fixed end
- > this movement of the wave towards the fixed end is a travelling wave
- note when the wave reaches the fixed boundary
- > it is reflected and inverted
- > these waves will then interfere with one another
What is a standing wave
- both ends of the string are fixed
- > in this case, the only apparent movement off the string is fluctuation of amplitude at fixed points along the length of the string
- note points where waves remain at rest or where amplitude is constant is referred to as a node
- > points midway between the nodes fluctuate with max amplitude and are known as antinodes
What is timbre
- it is the quality of the sound
- > determined by natural frequencies of the object
-natural frequencies of most objects can be changed by changing some aspect of the object itself
What is forced oscillation
- it is applying a periodically varying force to a system
- >the system is then driven at a frequency equal to the frequency of the force
When is the system resonatning
- if the forced oscillation frequency is equal to the natural frequency
- > then the amplitude of the oscillation is at a maximum
What is dampening or attenuation
-it is the decrease in amplitude of a wave caused by an applied or nonconservative force
