P12: Wave properties Flashcards
What is the nature of a wave?
It transfers energy but not matter
What is a transverse wave?
A wave in which the oscillations are perpendicular to the direction of energy transfer
What is a longitudinal wave?
A wave in which the oscillations are parallel to the direction of energy transfer. (particles move from side to side).
What are some examples of transverse waves?
Ripples in water
What are some examples of longitudinal waves?
Sound waves
What is a mechanical wave?
Vibrations that travel through a medium, e.g. sound waves, water waves, seismic waves.
What is an electromagnetic wave?
A wave which travels at the speed of light and does not need a medium to travel, e.g. radio waves, micro waves, light waves.
What are the features of longitudinal waves?
Regions where particles are close together - compressions
Regions where particles are far apart - rarefactions
What are the differences between longitudinal and transverse waves?
Long - require a medium to travel through, oscillation parallel to direction of energy transfer
Trans - can travel through space, oscillation perpendicular to direction of energy transfer
What is the amplitude of a wave?
The maximum displacement of a point on a wave, from the undisturbed position (line)
(drawn from rest to peak/ trough)
What is the wavelength of a wave?
The distance from a point on one wave to the equivalent point on the adjacent wave.
(drawn from peak to peak/ trough to trough ( transverse) or drawn from one compression to the next compression/ one rarefaction to the next rarefaction (longitudinal))
Represented by lambda (λ)
What is the frequency of a wave?
The number of waves passing a point each second (Hz)
1Hz = 1 wave per second
What is the formula for frequency?
Frequency = wavelength/ time
Hz no unit s
What is the period of a wave?
The time for one wave to pass a point
What is the formula for the period of a wave?
Period = 1/frequency
s Hz
What is wave speed?
The speed at which a wave moves through a medium/ the speed at which energy is transferred
What is the formula for wave speed?
Wave speed = frequency * wavelength
m/s Hz m
What are some problems with the sound wave experiment?
Every person has a different reaction time - can be reduced by having a large number of observers with timers, and calculate a mean.
Difficult to press the timer at the correct time since the interval is so short - fixed by increasing the distance between the two people.
How can you measure the speed of soundwaves in air?
Two people will stand a set distance apart e.g. 500 meters. One person will make a sound, e.g. with cymbals, and the other person will start a timer as soon as they see the instruments interact. They will then stop timing when they hear the sound of the cymbals clashing. Speed can be calculated by dividing the speed travelled by the time taken.
What happens to waves at the boundary between two different materials?
They are either reflected, transmitted or absorbed
What determines whether a wave is transmitted, reflected or absorbed?
The material and the wavelength of the wave
What is the rule for the angle of incidence?
Angle of incidence = angle of reflection
What are sound waves?
Longitudinal waves. They can pass through one medium to another.
How can sound waves be heard?
Sound waves are funnelled into the ear, where they hit the ear drum (thin membrane) and cause it and other parts of the ear to vibrate, causing the sensation of sound/