Module 2 Waves Flashcards
what is a transverse wave?
ocillations or vibrations which are perpendicular to the direction of energy transfer
what does a progressive way do? and what are some ways you can tell waves carry energy?
- a progressive wave carries energy from one place to another without transferring any material
- the transfer of energy is the same direction as the waves is travelling
e. g
1. ) electromagnetic waves cause things to heat up
2. ) X-rays and gamma rays knock electrons out of their orbit, causing ionisation
3. ) loud sounds cause large oscillations in air particles which can make things vibrate
4. ) wave power can be used to generate electricity
what are some examples of transverse waves?
- waves on the surface of warer
- any electromagnetic wave
- waves on stretched strings
- S-waves produced in earthquakes
what is a longitudinal wave?
in longitudinal waves the oscillations are parallel to the direction of the energy transfer
what are examples of longitudinal waves?
- sound waves
- p waves produced in earthquakes
suggesr why speed of sound is faster through a medium with higher density?
particles are closer together
strong restoring force/ vibrations are passed more rapidly from one particle to the next
what is the displacement of a wave?
give the symbol and unit
-how far a point on the wave has moved from it undisturbed position
symbol= x
unit= metres
what is the amplitude of a wave?
give the symbol and unit
the maximum magnitude of the displacement
symbol= A
unit= metres
what is the wavelength of a wave?
give the symbol and unit
the length of one whole wave cycle e.g from crest to crest ot trough to trough
symbol= λ
unit= metres
what is the period of a wave?
give the symbol and unit
the time taken for a whole cycle (vibration) to complete
symbol= T
unit= seconds
what is the frequency of a wave?
give the symbol and unit
the number of cycles (vibrations) per second passing a given point
symbol= f
units= hertz
what is the phase of a wave?
a measurement of the position of a certain point along the wave
unit= degree or radians
what is the phase difference of a wave?
-state unit
the amount one wave lags behind another
unit= degree or radians
what is a CRO oscilloscope? what does it do?
- a cathode ray osscilloscope measures voltage
- it displays waves from a signal generator as a function of voltage over time
- the displayed wave is called a trace
- the screen is split into into sqaures called divisions
- the vertical axis is in volts. the volts per division is controlled by the gain dial
- the horizontal axis is in seconds- also called the timebase. the seconds per divisions shown on this axis is controlled by the time base dial
- you can alter the gain and timebase to make it easy to read off measurements
the frequency is inverse of the period
show this in a equation
what are the units
f= 1/T
frequency= 1/Period
Hz= 1s-1
what are the eqautions for wave speed? what are you measuring in this eqaution?
wave speed= distance/ time
v= d/t
speed of wave= frequency x wavelength
v= fλ
you are measuring how fast a point on the wave pattern moves
if particles are oscilatting in step with each other (they both reach their maximum positive displacement at the same time) what are they described as?
in phase
they have a phase difference of 0
what is meant by a wave profile graph?
a graph showing the displacement of the particles in the wace against the distance along the wave
(the graph shows a snapshot of the wave)
what can a wave profile be used to determine?
- the wavelength of the wave
- amplitude of the wave
- the displacement (as the displacement of the particles in the wave is continously changing, the wave profile changes shape over time)
- )if two particles are seperated by distance of one whole wavelength what is the size of their phase difference?
- )what is they were two complete cycles out of step
- )360 degrees or 2π radians
- ) 720 degrees or 4π
if particles are oscillating completely out of step with each other then what are they described as being?
what is their phase difference?
the particles are described as being in antiphase
their phase difference is 180 degrees or π radians
when does reflection occur?
when a wave changes direction at a boundary between two different media, remaining in the original medium
what does a ray show?
the direction of energy transfer and so the path taken by the wave
what does the law of reflection state?
the law states that the angle of incidence is equal to the angle of reflection