What do waves do?
Transfer energy from one place to another without transferring matter
What is a wavefront?
A line joining points which vibrate in phase
What is wavelength
λ measured in m
The distance between a particular point on a disturbance and the same point on the next
What is frequency
The number of complete waves produced each second
The number of crests passing a chosen point each second
f measured in Hz
What is wave velocity?
v measured in ms^-1
The distance moved by any point on the wave in a second
Formula for wave velocity
v = f*λ
What is amplitude
A measured in m
The height of a crest (or depth of trough) measured from the undisturbed position of the medium carrying the wave
What is Time period
The time taken for a wave to be produced, or pass a chosen point
T measured in s
What is compression
The part of a longitudinal wave where the particles are closest together
What is rarefaction
The part of a longitudinal wave where the particles are furthest apart
What is in phase
Two points on a wave (or different waves) which have the same speed and direction of movement are said to be in phase
What is out of phase
Two points on a wave (or different waves) which have different speed and direction of motion are said to be out of phase
frequency = ?
1/T
1/Time period
When does diffraction occur?
When a wave passes an edge
Passes through a narrow gap
Goes past an object
No property of the wave is changed other than direction
What is the rule for diffraction?
If the slit (or obstacle) is similar in size to the wavelength, diffraction will occur best
What is a transverse wave?
Oscillations are perpendicular to the direction of energy transfer
What is a longitudinal wave?
Oscillations are parallel to the direction of energy transfer
What are examples of transverse waves?
Electromagnetic, ripples in water, guitar strings
What are examples of longitudinal waves?
Seismic P waves, Sound
How are transverse waves usually represented?
Displacement (m) vs Position (m) (Like a frozen photo) Displacement (m) vs Time (s) (The movement of one particle over time)
How are Longitudinal waves usually represented?
Displacement vs Position (Like a frozen photo of how particles are shifted back and forth at one instant)
Pressure vs Time (The variation of air pressure at one point as compressions and rarefactions pass)
What type of wave is sound
Mechanical
Longitudinal
What is a mechanical wave?
A wave that requires a medium to travel through
What do you need to produce sound
A vibrating object
