Waves Flashcards
Prove that waves carry energy and not matter
A buoy doesn’t move in water when there are waves, it just goes up and down
What is the frequency of a wave
number of waves that pass by a point during a given time
What is a wavefront?
Plane on which the wave travels
What is a period in a wave?
The amount of time it takes a wave to pass a certain point
What is a transverse wave?
Oscillations are at right angles to direction of travel. Has peaks and troughs.
What is a longitudinal wave?
The vibrations occur in the same direction as the direction of travel. Have compressions and rarefactions
How to test for wave speed in solids
Take a rod, suspend it in the air with rubber bands. Take a phone on the other side with a frequency app. Tap the rod. The phone will measure the peak frequency. Measure the length of the rod and times it by two. This is the wavelength. then use the wave speed formula
How does a wave behave when it reaches a boundary? 4 ways
reflect
refract
absorb
transmit
How do waves behave when they get transmitted through a less dense to a more dense medium.
They become slower
wavelength decreases
refracts towards the normal
State the laws for TIL
If the angle of incidence is less than the critical angle, most light is refracted out.
If the angle of incidence is more than the critical angle, the light is reflected internally.
If the AoI is the same as the critical angle, the ray travels along the boundary with some internal reflection
How does the ear work?
Sound waves that reach the eardrum cause it to vibrate at the same frequency as the sound wave.
These vibrations pass onto tiny bones attached to the eardrums which amplify the vibrations
The vibrations then pass through the semi-circular canal to the cochlea
the cochlea converts the vibrations into electric signals which gets sent to your brain
How does ultrasound get reflected?
When it hits a boundary, some of the wave is reflected off the boundary.
How is ultrasound used in foetal scanning?
Ultrasound passes through the body, however every time it hits a boundary some of the wave is reflected back. The computer uses the timing of how long the wave takes to return and its distribution to make a video image of the foetus
How is ultrasound used in industrial imaging?
Ultrasound is fired through metals. If there is a crack, it will reflect sooner than it would if it went the whole way down.
How is ultrasound used in sonar?
Reflects off the seabed and back to the boat.
