Progressive And Stationary Waves Flashcards
What is a progressive wave
Transfers energy without transferring material and is made up of particles of a medium oscillating
What is amplitude
A waves max displacement from the equilibrium position
What are the units for amplitude
m
What is frequency
The number of complete oscillations passing through a point per second
What are the units for frequency
Hz
What is wavelength
The length of one whole oscillation
What is the unit for wavelength
m
What is the speed
Distance travelled by the wave per unit time
What is the unit of speed
m/s
What is phase
The position of a certain point on a wave cycle
Why are the units for phase
Radians, degrees or fractions of a cycle
What is phase difference
How much a particle/wave lags behind another particle/wave
What are the units for phase difference
Radians, degrees or fractions of a cycle
What is a period
Time taken for one full oscillation
When are two point in phase
If they are both at the same point of the wave cycle they will have the same displacement and velocity and their phase difference will be a multiple of 360°
If two points are in phase what do they need to have the same out of frequency amplitude and wavelength
Frequency and wavelength
When are two points out of phase
When they are a half cycle apart (180°)
What is the equation for the speed of a wave
Speed = frequency x wavelength
What is the equation for the frequency of a wave
Frequency = 1/period
What are transverse waves
Oscillations of particles is at right angles to the direction of energy transfer
Are electromagnetic waves longitudinal or transverse
Transverse
What speed to electromagnetic waves travel at
3 x10 ^8
How can transverse waves be demonstrated
By shaking a slinky vertically or through the waves seen on a string when attached to a signal generator
What are longitudinal waves
Oscillations of particles is parallel to the direction of energy transfer
What are longitudinal waves made out of
Compressions and rarefractions
How can a longitudinal wave be demonstrated
By pushing a slinky horizontal
what is a polarised wave
a transverse wave that oscillates in only one plane
what does polarisation provide evidence for
the evidence for the nature of transverse waves because polarisation can only occur if a waves oscillations are perpendicular to its direction of travel
how do polarised sunglasses reduce glare
by clocking partially polarised light reflected from water or tarmac as they only allow oscillations in the plane of the field making it easier to see
how do TV and radio signals use polarisation to work
they plane polarised by the orientation of the rods on the transmitting aerial so the receiving ariel must be aligned in the same plane of polarisation to receive the signal at full strength
what is superposition
is where the displacements of two waves are combined as they pass each other
what is the resultant displacement in superposition
is the vector sum of each waves displacement
what are the two types of interference
constructive and destructive
how does constructive interference occur
occurs when 2 waves have displacement in the same direction
how does destructive interference occur
occurs when on wave has positive displacement and the other has a negative displacement
what needs to happen to get total destructive interference
when the waves have equal but opposite displacements
what does a stationary wave form from and what needs to be the same
the superposition of 2 progressive waves travelling in opposite directions in the same plane with the same frequency, wavelength and amplitude
do stationary waves transfer energy
no
when waves meet in phase which interference occurs and what forms there
constructive interference and antinodes are formed
when waves meet out of phase which interference occurs and what forms there
destructive interference and nodes are formed there
what are antinodes
regions of maximum amplitude
what are nodes
regions of no displacement
what is an example of how to form a stationary wave
a string fixed at one end and the other end fixed to a driving oscillator
how does a stationary wave form when fixed at one end and the other fixed to a driving oscillator
a wave travelling down the string from the oscillator will be reflected at the fixed end of the string and travel back along the string causing superposition of the two waves and because the waves have the same wavelength frequency and amplitude a stationary wave is formed
what is the lowest frequency at which a stationary waves formed called
the first harmonic
how many nodes and antinodes are in the first harmonic
two nodes and one antinode
how do you find the frequency of the second harmonic from the first
double it
how are stationary microwaves formed
by reflecting a microwave beam at a metal plate to find the nodes and antinodes use a microwave probe
how are stationary sound waves formed
can be formed by placing a speaker at one end of the closed glass tube lay powder across the bottom of the tube it will be shaken at the antinodes and settle at the nodes as you then know the frequency and wavelength you can work out speed of sound
