P12- Wave Properties Flashcards
What is a transverse wave?
Which waves are all transverse waves?
1) A transverse wave is a wave that oscillates perendicular to the energy transfer of the wave.
2) All electromagnetic waves are transverse waves. The ripples on a water surface are an exmale of a transverse wave.
What is a longitudinal wave?
Give an example of a longitudinal wave.
1) A longitudinal wave oscillates parallel to the direction of energy transfer of the waves.
2) Sound waves in the air are longitudinal waves.
What do mechanical waves need in order to travel through?
What type of wave can they be?
1) Mechanical waves need a medium (substance) to travel through.
2) They can either be a transverse wave or a longitudinal wave.
Give the formula for Period.
What is Period?
1) Period = 1/Frequency
2) Period is the time taken for each wave to pass a fixed point.
What is the amplitude of a wave?
What is the wavelength of a wave?
1) The amplitude of a wave is the maximum displacement of a point on a wave away from its undisturbed position.
2) The wavelength of a wave is the distance from a point on one wave to the equivalent point on the adjacent wave.
Give the formula for wave speed.
What is wave speed?
1) Wave speed = frequency x wavelength.
2) Wave speed is thhe speed at which the wave move through the medium.
What is the refraction of waves?
1) Refraction of waves is the change of direction in which they are travelling when they cross a boundary between one medium and another medium.
How are plane waves in a ripple tank reflected?
1) Plane waves in a ripple tank are reflected from a straight barrier at the same angle to the barrier as the incident waves because their speed and wavelength do not change on reflection.
When are plane waves refracted?
1) Plane waves crossing a boundary between two different materials are refracted unless they cros the boundary at normal incidence.
What happens at a boundary?
1) At a boundary between 2 different materials, waves can be transmitted or asorbed.
What are sound waves?
Where can they not travel?
1) Sound waves are vibrations that travel through a medium.
2) They cannot travel through a vacuum (eg: space)
What happens to the pitch of a note when something to do with frequency changes?
What happens to the loudness of a note when something to do with amplitude changes?
1) The pitch of a note increases if the frequency of the sound waves increases.
2) The loudness of a note increases if the amplitude of the sound waves increases.
What do sound waves cause the ear drums to do?
1) Sound waves cause the ear drums to vibrate and therefore send signals to the brain.
What is the range of frequency that a human ear can detect?
1) 20hz - 20,000hz.
Why is human hearing limited?
1) Human hearing is limited because the conversion of sound waves to vibration of solids works over a limited fequency range.
What is an ultrasound wave and what are their uses?
1) An ultrasound wave is a wave that has a frequency which is higher than the upper limit of hearing for humans.
2) Ultrasound waves can be used for medical and industrial imaging.
What is an ultrasound scanner made up of?
1) An ultrasound scanner is made up of a transducer placed on the body surface, a control system and a display screen.
When might ultrasound waves be reflected?
1) Ultrasound waves might be reflected when they meet a boundary between two different media.
What happens to each ultrasound wave pulse from the transducer?
1) It is partially reflected from the different tissue in its path.
2) It then returns to the transducer as a sequence of ultrasound waves reflected by the tissue boundaries, arriving back at different times.
Why are ultrasound waves partly reflected by body organs?
1) They are reflected at boundaries between different types of tissue so that they can scan organs and other soft tissues in the body.
What is a seismic wave?
How are they produced?
1) A seismic wave is a wave that travels through the earth.
2) Seismic waves are produced in an earthquake and spread out from the epicentre.
What type of waves are P waves and S waves?
What do they provide evidence for?
1) A Primary Seismic wave (P Wave) is a longitudinal wave.
2) A Secondary Seismic wave (S Wave) is a transverse wave.
3) They provide evidence for the structure and size of the earth’s core.
Explain the strcture of the earth.
1) The earth has a solid inner core surrounded by a liquid outer core, surrounded by the mantle. The mantle is surrounded by the earth’s crust.
