Waves 6.1 Flashcards
All wavesare either:
- transverse
- longitudinal
what type of wave is ripples on the surface of the water
-transverse wave
what type of wave are sound waves travelling in air
-longitudinal waves
all waves transfer energy from one place to another
how do ripples on the surface of water transfer energy
how do sound waves transfer energy
- ripples transfer kinetic energy
- sound waves transfer sound energy
the waves move up and down
what do scientists call these movements
-oscillations
what are the oscillations like in transverse waves
in transverse waves, the oscillations are perpendicular to the direction of energy transfer.
in transverse waves
oscillations are up and down but the direction of energy transfer is sideways
a good example of longitudinal waves are sound waves
sound waves travel as particles in the air move from side to side.
there are regions where the particles are very close together and scientists call these regions compressions.
in between the compressions, there are regions where the particles are spaced out, these regions are called rarefactions.
in longitudinal waves the oscillations are parallel to the direction of energy transfer.
aside from that difference, there is also another difference between transverse and logitudinal waves all longitduinal waves require a medium to travel
give examples of a mediumf
air
liquid
solid
do transverse waves require a medium
no, not all transverse waves require a medium
for both ripples on a water surface and sound waves that travel through air its the wave that travels and not the water or the air.
the air particle or water particle does not travel through the medium, it moves side to side with the oscillations (in the sound wave longtudinal) or it moves up and down with the oscillations (in a ripple on the surface of water transverse)
free science lessons exercise: what type of waves are water waves and what type of energy is transferred
- water waves are transverse waves
- water waves transfer kinetic energy
free science lessons exercise: what type of waves are sound waves and what type of energy is transferred in sound waves
sound waves are longitudinal waves
-sound waves transfer sound energy
free science lessons exercise: correct the statement
the movement of the transverse wave sideways is called an oscillation
correct statement- movement of the transverse wave up and down is called oscillation
correct the statement
in transverse waves the oscillations are parallel to the direction of energy transfer
-correct statement: in transverse waves the oscillations are perpendicular to the direction of energy transferred
correct the statement: in the transverse wave above, the direction of energy transfer is up and down
correct statement- in a transverse wave the direction of energy transfer is sideways from left hand side to right hand side
correct the statement: water waves are longitudinal
correct statement: water waves are transverse waves
fill in the gaps
in transverse waves the oscillations are ———– to the direction of energy transfer
perpendicular means at ———- angles
in transverse waves the oscillations are perpendicular to the direction of energy transfer
perpendicular means at right angles
in compression, the particles are
select the right option
-further apart
-closer together
in compression, particles are closer together
in rarefaction particles are:
select right option
-further apart
-closer together
in rarefaction particles are further apart
in longitudinal waves, how can you link direction of energy transfer and direction of oscillations
iin longitudinal waves, oscillations are parallel to direction of energy transfer.
what is another difference between longitudinal and transverse waves
-longitudinal waves travel through a medium air , liquid or solid
not all transverse waves require a medium to travel.
an example is that, light is a transverse wave and it travels through a vacuum( no particles)
in both water waves and sound waves in air its the wave that travels and not…
the water or air.
water or air particles do not travel through the medium, they move with the oscillations up and down (transverse) or sideways from left to right (longitudinal)
what are compressions,
in sound waves or other longitudinal waves there are regions where the particles are very close together. these regions are known as compressions
what are rarefactions
in between compressions, these are regions where particles are more spaced out, they are further apart
-Describe the differences between
transverse and longitudinal waves and give
examples
transverse waves- examples are water waves and ripples , light waves
wave on a string
electromagnetic waves
in transverse waves, the oscillations are perpendicular to the direction of energy transfer,
the oscillations are up and down whereas the direction of energy transfer is sideways from left hand side to right hand side.
transverse waves do not require a medium to travel through for example light waves are transverse but travel through a vacuum.
longitudinal waves examples include, sound waves in air (ultrasound)
some seismic waves
in longitudinal waves, the oscillations are parallel to the direction of energy transfer.
all longitudinal waves travel through a medium eg air, liquids and solids
definition of amplitude
maximum displacement of a point on a wave away from its undisturbed position
definition of wavelength
wavelength of a wave is a distance from a point on one wave to the equivalent point on a adjacent wave
symbol of wavelength is greek lambda
how do you measure wavelength on longitudinal waves
measure from one compression to the next compression or from one rarefaction to the next rarefaction
definition of frequency
number of waves passing through a point each second
1HZ= 1 wave per second
to find the frequency from a diagram count number of complete waves and divide by the number of seconds to tell you the number of waves per second/
definition of period
the period is the time (in seconds) for one wave to pass a point.
period can be calculated by
1/ frequency
definition of wavespeed
the wavespeed is the speed at which the wave moves through the medium (the speed at which energy is transferred)
equation for wavespeed
frequency x wavelength
Hz x m =m/s
method to measure speed of soundwaves in air
two people are separated by a distance of 500 m
person A holds the cymbals person B holds a timer
person B starts timing when they see person A clash the cymbals together
Person B stops timing when they hear sound of cymbals crashing
the speed of the sound waves can be calculated by dividing the distance travelled by the time taken
what are some problems with the experiment of measuring the speed of sound waves in air
-every person has a different reaction time
it takes a fraction of a second between seeing the cymbals and starting the timer it also takes a fraction of a second before hearing the sound of the cymbals and stopping the timer
we can reduce this error by having a large number of observers with timers
we can take all the results and discard any that are anomolous
we can also calculate a mean value
it takes a very short time between seeing the cymbals crash and hearing the sound, that makes it difficult to press the timer at the correct times. we can reduce this error by increasing the distance between person A and person B. the longer the distance the longer the time, that makes it easier to start and stop the timer at the correct times.
required practical ripple tank
we are measuring the wavelength frequency and speed of water waves
give definitions of all three
wavelength- distance from one point on a wave to the equivalent point on an adjacent wave
frequency- number of waves passing through a point each second
1hz= 1 wave per second
wavespeed- speed at which the wave moves through the medium or speed at which energy is transferred
remember water waves transfer kinetic energy
equation= wavespeed= frequency x wavelength
what does a ripple tank do/ why is it used
a ripple tank is used to determine the features of water waves
how does the experiment work
a ripple tank is a shallow tray of water and in the water is a vibrating bar which is connected to a power pack
when the bar vibrates it creates waves across the surface of the water
above the ripple tank is a lamp and below the ripple tank is a sheet of white paper
when light shines through the water, it produces an image of the waves on the paper
how do we measure the wavelength using a ripple tank wavelength definition ( distance from one point on a wave to the equivalent point on an adjacent wave)
to measure wavelength place a ruler on the paper. freeze the image of the waves.
measure the distance between one wave and 10 waves further (a total of ten wavelengths)
to find one wavelength divide this by ten
how do you measure frequency using ripple tank experiment
frequency= number of waves passing a point each second
1hz= 1 wave per second
place a timer next to paper and count number of waves passing a point in 10 seconds. now divide the number of waves by 10 to calculate number of waves passing a point each second. ( counting number of waves passing the point in ten seconds gives more accurate results than measuring for one second)
we can make this easier by recording this and watching it in slow motion, in this case you would need to also record the timer as well as the waves.
how to determine wavespeed from ripple tank experiment
we already know wavelength and frequency of waves so we can use this to determine the wavespeed by multiplying the wavelength and the frequency.
wavespeed m/s= frequency hz x wavelength m
whats another way to determine wavespeed using ripple tank experiment, other than using the wavespeed equation
- select a wave
-measure time taken for wave to move the length of the tank
divide the distance travelled by the wave by the time taken for it to move the length of the tank.
we might get two slightly differnet results using these two methods to determine wavespeed of the water waves
what is this due to
-measurement errors eg timing
describe apparatus of required practical for waves in a solid
we have a string with one attached to a vibration generator.
we have a hanging mass at the other end of the string
the mass keeps the string taut
the vibration generator is attached to a signal generator
the signal generator allows us to change the frequency of vibration of the string
when we turn on the power, the string vibrates
at a certain frequency we produce a standing wave
what is a standing wave caused by
effect of resonance.
where do we find standing waves
in stringed instruments such as a guitar
how do we measure wavelength of a standing wave
use a ruler
measure total length of standing wave from vibration generator to wooden bridge.
we can use the wavelength to calculate the speed of the wave
use the wave equation
wavespeed m/s= frequency Hz x wavelength m
read the frequency from the signal generator.
what happens if we increase the frequency
the standing wave changes
we get three halfwavelengths
how do we calculate wavelength of the changed standing wave ( increased frequency causes standing wave to change)
to calculate wavelength divide total length from wooden bridge to vibration generator by number of halfwavelengths and then multiply by 2