P12 Wave Properties (paper 2) Flashcards
Define waves
Waves transfer energy with out transferring matter
What are all waves casued by
oscillating particles
What is the equation for frequency
Frequency = velocity / wavelength
What are transverse waves
Waves where the particles oscillate perpendicular to the direction of energy transfer
What direction are transverse waves
Up and Down
What are examples of transverse waves
- tidal wave
- electromagnetic wave
- Seismic S wave
What is a
wavelength
what is b
peak or creast
what is c
trough
what is d
amplitude
what is e
direction of energy transfer
what is f
direction of oscillations
What are logitudinal waves
Waves where the particles oscillate parallel to the direction of energy
what direction are the osscillations of a logitudinal wave
forward and backward / side to side
What are examples of logitudinal waves
- sound waves
- ultra-sound waves
- seismic P waves
what is a
wavelength
what is b
amplitude
what is c
rarefaction
what is d
compression
what is e
direction of energy transfer
what is f
direction of oscillation
When does sound travel fastest and why
in solids becuase the particles are closer together so the vibraions are easily transfered
Do sound waves need a medium to travel through and why
yes becuase in a vacuum there are no particles to transfer energy to
What are the two methods to measure the speed of time
- clap-echo method
- microphones and data-logger method
what is the boundary for sound
20Hz - 20,000Hz
what is the boundary for ultra-sound
20,000Hz +
what is the boundary for infrasound
> 20Hz
What are the uses of ultrasound
- clean jewelery
- pre-natal scan
- detect cracks inside metal structures
- detect is gold is real
what is the equation for distance
distance = speed x time
explain the method of the clap-echo method
- stand 50m away from a wall
- measure the time taken for a clap to echo from the wall
- speed = (distance / time)/2
explain the microphone and data-logger method
- you have 2 microphones and 1 data-logger
- data-logger measure and records time taken for sound to reach the microphones
- speed = distance/time
What are the benefits of the microphones and data-logger method
- higher resolution and therefore more accuracy
- no chance for human error
What is the equation relating time period and frequency
time period = 1 / frequency
What do you use to measure the speed of sound
oscilloscope
Can all waves be reflected
yes
What are the three things that can happen when a wave arrives at a boundary
- absorbed by the material
- trasmittedd through the material [leading to refraction]
- reflected off the material
how does the angle of incidence relate to the angle of reflection
angle of incidence = angle of reflection
what is the angle of incidence
the angle between the incoming wave and the normal
what is the angle of reflection
the angle between the reflected wave and the normal
What is the normal
an invisable line that is perpendicular to the surface at the point of incidence
What is a
the normal
what is b
the reflected ray
what is c
the incoming ray
What is d
the angle of incidence
what is e
the angle of reflection
What are the two different way waves can be reflected
- specular
- diffuse
what is specular reflection
when a wave is reflected in a single direction by a smooth surface
what is diffuse reflection
when a wave is reflected by a rough surface and the reflected rays are scatted in lots of different directions
What types of waves are electromagnetic waves
transverse
What is refraction
when a wave crosses a boundary between materials at an angle and it changes direction because it changes speed
What will happen to a wave if it crosses a boundary and slows down
it will bend towards the normal
what will hapen is the wave crosses into a material and speeds up
the wave will bend away from the normal
What happens to the wave physically when it is refracted
- the wavelength changes but the frequency stays the same so the waves speed up when the wavelength grows etc
if the wave is travelling along the normal will it refract
no but it will chnage speed
if the optial density is higher in a material then how does speed of the wave change
it will get slower
how do the angle of incidence and the angle of refraction relate
angle of incidence > angle of refraction
How do we measure the layers of the earth
with Seismic waves
What are the two types of seismic waves
- primary waves
- secondary waves
what are seismic waves
the energy transferred when forces inside the earth increas and become strong enough to break rock
what are P-waves
they are logitudinal waves that cause intitial termours that are refracted when they enter the outer core
what are S-waves
they are transverse waves that cannot travel through the outer core
what happens when seismic waves travel through the mantle
- bend
- speed changes gradually ewith depth
- therefore so does direction
What is the shadow zone
a zone where no P or S waves are recorded becuase P waves are refracted and S waves cannot travel through liquid
How do you convert something to a milli (m)
x1,000
x10^3
How do you convert something to a micro (μ)
x1,000,000
x10^6
how do you convert something to a kilo (k)
/1,000
x10^-3
How do you convert something to a mega (M)
/1,000,000
x10^-6
How do you convert something to a giga (G)
x1,000,000,000
x10^-9
If the refracted index is lower with the wave speed up or slow down
speed up
What angle must the angle of incidence be between
0 - 90 degrees
describe how ultrasound is used in pre-natal scans
- the ultrasound waves pass through the body
- they reach the boundary between the fuild in the womb and the feotus’ skin
- wave is reflected and detected and then processed by a computer
- an image is created
