Physics Waves AQA AS Questions and Answers 100% Pass
How does a wave transfer energy through a medium?
By causing the particles in the medium to oscillate
Which measurement can take a negative value?
Displacement
What are the units of displacement?
metres (m)
What are the units of amplitude?
metres (m)
What are the units of frequency?
hertz (Hz)
What is meant by a period of a wave?
The time taken for one whole wave cycle
What is meant by the frequency of a wave?
The number of whole wave cycles (oscillations) per second passing a given point.
What is meant by the phase of a wave?
a measurement of the position of a certain point along the wave cycle.
What is meant by the phase difference of a wave?
the amount by which one wave lags behind another wave.
How would you calculate the frequency of a wave, given its period?
frequency= 1/period
What is the difference between transverse and longitudinal waves?
In transverse waves, the direction of displacement of the particles/fields (the vibrations ) is at right
angles to the direction of energy transfer, whereas in longitudinal waves the direction of
displacement of the particles/fields is along the direction of energy transfer.
What happens when you put two polarising filters at right angles in front of a beam of light.
No light gets through
What happens to unpolarised light when it is reflected from the surface of water.
It is partially polarised - some of the vibrations of the reflected light are in the same direction.
Explain how Polaroid sunglasses reduce glare.
, Light is partially polarised when reflected by some materials. Polaroid sunglasses block out light in the
direction in which the reflected light is partially polarised, but let through light vibrating in other
directions. This reduces glare without reducing visibility.
Other than polarising sunglasses, give one example of how polarised waves are relevant to everyday
life.
Reducing reflections in photography / aligning TV and radio receivers.
What does the principle of superposition say?
When two or more waves meet, the resultant displacement equals the vector sum of the individual
displacements.
Describe constructive interference.
When two waves pass through each other and their displacements combine to make a displacement
with a greater magnitude.
What is total destructive interference?
When two waves pass through each other and their displacements cancel each other out completely.
What is the phase difference of two points on a wave?
The phase difference of two points on a wave is the difference in their positions in the wave's cycle.
Give three possible units for phase difference.
degrees, radians or fractions of a cycle.
When are two points on a wave exactly out of phase?
When their phase difference is an odd multiple of 180 degrees (pi radians or half a cycle)
What does it mean for two waves to be in phase?
Two waves are in phase if they have a phase difference of 0 degrees (or a multiple of 360 degrees)
How is a stationary wave formed?
When two progressive waves are travelling in opposite directions with the same frequency (or
wavelength) and the same amplitude, their superposition creates a stationary wave.
Does a stationary wave transfer energy.
No
Describe what a resonant frequency of a string is.
A resonant frequency of a string is a frequency at which a stationary wave is formed because an exact
number of waves are produced in the time it takes for a wave to get to the end of the string and back
again.
Give an example of a way to observe stationary sound waves.
How does a wave transfer energy through a medium?
By causing the particles in the medium to oscillate
Which measurement can take a negative value?
Displacement
What are the units of displacement?
metres (m)
What are the units of amplitude?
metres (m)
What are the units of frequency?
hertz (Hz)
What is meant by a period of a wave?
The time taken for one whole wave cycle
What is meant by the frequency of a wave?
The number of whole wave cycles (oscillations) per second passing a given point.
What is meant by the phase of a wave?
a measurement of the position of a certain point along the wave cycle.
What is meant by the phase difference of a wave?
the amount by which one wave lags behind another wave.
How would you calculate the frequency of a wave, given its period?
frequency= 1/period
What is the difference between transverse and longitudinal waves?
In transverse waves, the direction of displacement of the particles/fields (the vibrations ) is at right
angles to the direction of energy transfer, whereas in longitudinal waves the direction of
displacement of the particles/fields is along the direction of energy transfer.
What happens when you put two polarising filters at right angles in front of a beam of light.
No light gets through
What happens to unpolarised light when it is reflected from the surface of water.
It is partially polarised - some of the vibrations of the reflected light are in the same direction.
Explain how Polaroid sunglasses reduce glare.
, Light is partially polarised when reflected by some materials. Polaroid sunglasses block out light in the
direction in which the reflected light is partially polarised, but let through light vibrating in other
directions. This reduces glare without reducing visibility.
Other than polarising sunglasses, give one example of how polarised waves are relevant to everyday
life.
Reducing reflections in photography / aligning TV and radio receivers.
What does the principle of superposition say?
When two or more waves meet, the resultant displacement equals the vector sum of the individual
displacements.
Describe constructive interference.
When two waves pass through each other and their displacements combine to make a displacement
with a greater magnitude.
What is total destructive interference?
When two waves pass through each other and their displacements cancel each other out completely.
What is the phase difference of two points on a wave?
The phase difference of two points on a wave is the difference in their positions in the wave's cycle.
Give three possible units for phase difference.
degrees, radians or fractions of a cycle.
When are two points on a wave exactly out of phase?
When their phase difference is an odd multiple of 180 degrees (pi radians or half a cycle)
What does it mean for two waves to be in phase?
Two waves are in phase if they have a phase difference of 0 degrees (or a multiple of 360 degrees)
How is a stationary wave formed?
When two progressive waves are travelling in opposite directions with the same frequency (or
wavelength) and the same amplitude, their superposition creates a stationary wave.
Does a stationary wave transfer energy.
No
Describe what a resonant frequency of a string is.
A resonant frequency of a string is a frequency at which a stationary wave is formed because an exact
number of waves are produced in the time it takes for a wave to get to the end of the string and back
again.
Give an example of a way to observe stationary sound waves.
