P12 Waves Flashcards
Equation for wavespeed?
Wavespeed = frequency x wavelength
Transverse waves
Wave oscillations are perpendicular to direction of energy transfer
Longitudinal waves
Wave oscillations are parallel to direction of energy transfer
What happens when wave arrives at a boundary?
Waves can either be absorbed, transmitted or reflected
What happens when a wave is reflected in a single direction by a smooth surface?
Specular relection
What does the size of the amplitude of the wave mean?
The larher the amplitude of the wave, the more energy the wave carries
What is frequency
The time taken for each wave to pass a fixed point measured in hertz
1 wave crest passing a point in 1 second is equal to 1Hz
What is a period of a wave
Time taken for each wave to pass a fixed point
Equation that links frequecny and period
Period (seconds) = 1
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Frequency (Hz)
Equation for wavespeed
Wave speed (m/s) = Frequency (Hz) X Wavelength (m)
Example of a transverse wave
Ripples on surface of water
Example of longitudinal waves
Sound waves travelling through air
What is the amplitude of a wave
The maximum displacement point of a wave from it’s undisturbed position
What is the method to find speed of sound waves in a ir?
2 people
Stand far away from eachother in a field
Measure distance between eachother
Get 1 person to clash cymbals
Other person holds stopwatch
Start stopwatch when you see cymbals clash and stop when you hear the sound
Repeat to get an average time interval
Speed = distance divided by time
What is refraction
When the wave crosses a boundary at a non-zero angle to the boundary, the wave will change in speed and direction
If wavefronts move slower at the non-zero angle boundary the wavefront will be at a smaller angle to the boundary and closer together
Rules for refracted waves
Refracted wave and incident wave will have the same frequency but travel at different speeds so they have different wavelengths
What happens when a wave is absorbed by a substance?
Ehen a wave is absorbed by a substance, the substance will:
Gains energy from the waves
Therefore heat the substance will heat up
What happens when a wave is transmitted by a substance?
The waves are transmitted
E.g. glass mostly transmits light waves
Learn wave practical
Stupid!
What is the normal range of human hearing?
20Hz - 20kHz
How can humans hear?
Sound waves can travel through solids causing vibrations in the
solid.
Within the ear, sound waves cause the ear drum and other parts to
vibrate which causes the sensation of sound. The conversion of
sound waves to vibrations of solids works over a limited frequency
range. This restricts the limits of human hearing.
What are ultrasound waves?
Sound waves that have a frequency higher than the limit of human hearing
How do ultrasound scans work?
- Ultrasound waves are partially reflected when they meet a boundary
- The time taken for the reflections to reach a detector can be used to determine how far away such a boundary is.
- This allows ultrasound waves to be used for both medical and industrial imaging.
What are the 2 different types of seismic waves?
Primary waves
And
Secondary waves
What are Primary seismic waves?
- P-waves
- Longitudinal seismic waves
- Travel at different speeds through solids and liquids
What are Secondary seismic waves?
- S-waves
- Transverse waves
- Cannot travel through a liquid
What is a transverse wave?
Oscillations of transverse wave are perpendicular to the direction of energy transfer
What is a longitudinal wave?
Oscillations of a Longitudinal wave are parallel to the direction of energy transfer
What is echo sounding?
Uses high frequency sound waves to measure depth of water and detect objects in deep water
How are sound waves produced by an object vibrating in air?
Vibrating object pulls and pushes repeatedly on air
This sends out vibrations of air of compressions and rarefractions
The waves are longitudinal
Why is it important the human tissue does not absorb ultrasound waves in medical scanners?
If it was absorbed, the wave wouldn’t be detected
