Waves Flashcards
Waves
Transfers energy without transferring matter
Frenquencey
The number of waves passing a point per second- Hz
transverse waves
Oscillations are perpendicular to the wave direction
Longitudinal
Oscillations are parallel to the wave direction
Time period
The time taken for one complete wave to pass a point
Amplitude
The maximum height of the wave taken from the displacement or rest line to the peak
Wavelength
The distance from peak to peak or trough to trough
Wave speed equation
Wavelength x frequency= wave speed
Wave speed = distance / time
Waves being absorbed
The wave transfers energy to the materials energy stores
Often energy is transferred to a thermal energy store
Waves transmitted
The wave carries on travelling through the new material - leads to refraction
Used in communications
Lenses glasses and cameras
Waves reflected
Where the incoming ray is not transmitted or absorbed but is sent back away from the second material
Echoes
Water evidence
If you drop a twig into a pool of water, ripples form on and move across the waters surface
-the ripples don’t carry the water or the twig away
Sound evidence
If you strum a guitar string and create a sound wave, the sound wave travels to your ear
It doesn’t carry the air away
Examples of transverse waves
All electromagnetic waves
S-waves
Ripples and waves in water
Longitudinal waves example
Sound waves
P-waves
How do longitudinal waves move?
They squash and stretch out the arrangement of particles in the medium they pass through
Making compressions and refractions
Wave velocity
The speed at which a wave moves
Wave front
A surface containing points affected by the same wave at a given time
How do you measure the velocity if sound in air?
Set up oscilloscope - detected waves at each microphone are shown as separate waves
Start with two microphones next to the speaker -slowly move 1 away
Measure distance between the microphones to find 1 wavelength
Use formula wave speed = wavelength x frequency
How do you measure the speed of water ripples using a strobe light?
Attach the signal generator to the dipper of a ripple tank - you can set waves at a set frequency
Turn on strobe light - see wave pattern
Alter the frequency of light
Distance between each shadow length is equal to 1 wavelength
Measure the distance
How do you find the speed of waves in solids?
By measuring the frequency of sound and waves
Measure + record the length of a metal rod
Set up the apparatus making sure to the rod at its centre
Tap the rod with the hammer - write down frequency
Repeat 3 times - average
Calculate wave speed
Wave behaviour at boundaries - absorbed
The wave transfers energy to the materials energy stores
Energy is often transferred to a thermal energy store
Wave behaviour at boundaries - transmitted
The wave carries on travelling through the new material which leads to refractions
It’s used in communications
And lenses of glasses and cameras
Wave behaviour at boundaries - reflected
Where the incoming ray is not transmitted or absorbed bit is sent back away from the second material
