p5-waves basic waves, superposition, interference Flashcards
What is the Amplitude of a wave ?
A waves maximum displacement from the equilibrium position
What is the wavelength of a wave?
The distance between two identical points on a wave/ the length of one whole oscillation
what is the period of a wave?
The time it takes for the wave to repeat itself at a given point/ Time taken for one oscillation
What is the frequency of a wave?
The number of complete oscillations passing through a point per second
How are period and frequency linked ?
frequency=1/ period and period=1/frequency
What is superposition?
When two or more waves cross at a point, the displacement at that point is equal to the sum of the displacement of individual waves.
What is the definition of phase?
The position of a certain point om a wave cycle. This can be measured in radians or degrees or a fraction of a cycle
What is phase difference?
How much a particle/ wave lags behind another particle/wave. This can be measured in radians, degrees or fractions of a cycle
What is path difference?
The difference in distance travelled by two waves
What is coherence?
when the waves have the same frequency and a constant phase difference
What is a wavefront?
A wavefront is a surface which is used to represent the points of a wave which have the same phase.
What is the phase relationship between phase difference and path difference?
They are directly proportional?
What is the equation for phase difference?
phase difference= 360x path difference/wavelength
What is the minima of a wave?
The point where a crest and a trough of two different wavefronts meet
What is the maxima of a wave?
The point where two crests or two troughs of two different waves meet
what is the equation for working out the velocity of a wave?
wave speed=frequency x wavelength
What are longitudinal waves?
The oscillations parallel to the direction of energy transfer.
These are made up of compressions and rarefactions.
Cannot travel in a vacuum.
What is happening at rarefactions?
Low pressure.
Neighbouring particles move away from one another.
What is happening at compressions?
High pressure.
Neighbouring particles move towards a particle.
What are transverse waves?
The oscillations are perpendicular to the direction of the wave.
Consist of peaks and troughs.
Can travel in a vacuum.
What is an S-wave ?
They are transverse waves that travel through the earth in a earthquake, they can travel through liquid so arrive after P-waves as they are slower.
What are P-waves?
They are longitudinal waves that travel thought the earth in a earthquake. They cannot travel through liquid and are faster so arrive at the surface first.
What can a Displacement/ Distance graph show for a wave?
Shows the displacement of a particle with the distance the wave travels. Used to measure the wave length.
What can Displacement/Time graph show for a wave?
Show the displacement of a particle varies with time. Can be used to measure the period of a wave.
What is constructive interference ?
Occurs when the two waves are in phase, so there displacement are added.
What is destructive interference?
This occurs when two waves are completely out of phase, so their displacements are subtracted.
What is a progressive wave?
A wave the
at transfers energy from one point to another, without transferring matter.
What is a standing wave?
A wave that transfers energy rather than transferring it from one place to another.
What is 90 degrees in radians?( 0.25λ)
π/2
What is 180 degrees in radians?(0.5λ)
π
What is 270 degrees in radians?(0.75λ)
3π/2
What is 360 degrees in radians?(1λ)
2π
What is 540 degrees in radians?(1.5λ)
3π
What in 720 degrees in radians(2λ)
4π
How are standing waves formed on a string?
A wave reflects at a closed end meaning two identical waves are travelling in opposite directions down the same string.
The waves must be coherent for a standing wave to from.
At point where the waves meet in phase, constructive interference occurs and antinodes form.
At points where the waves meet in antiphase, destructive interference occurs and nodes are formed.
What are nodes?
A node is a point of minimum displacement- there is no movement from the equilibrium position.
What are antinodes?
An antinode is a point of maximum displacement.
What factors does the speed of a transverse wave on a string depend on? (Core practical for finding the fundamental frequency)
Tension and mass per unit length of string( mew)
What is the equation for working out the speed of a transverse wave on a string?
v=√T/μ
What do Oscilloscopes show?
The time period for one wave cycle
