U3 - Waves
What is amplitude? MAXIMUM displacement from rest position.
What is frequency (in terms The number of waves passing through a point each second
of waves)? (measured in Hz or s-1).
What is wavelength? The distance between two identical consecutive points.
What is time period? The time taken for one complete wavelength to pass a point.
What are mechanical waves Waves that rely on a medium to travel through (e.g., sound waves
(with examples)? and seismic waves).
What are electromagnetic
waves?
Oscillating electric and magnetic fields that are in phase and
perpendicular to one another.
Give 3 properties of ● Can travel through a vacuum.
electromagnetic waves ● Travel at the speed of light (through a vacuum).
● Are all transverse.
What are the sections of the
electromagnetic spectrum Name Properties
and the properties of either
side? Radio Longest wavelength ⇒ lowest frequency ⇒ least
penetrating.
Microwaves, Infrared, Visible, Ultraviolet, X-ray
Gamma Shortest wavelength ⇒ highest frequency ⇒ most
penetrating.
In what range does visible 400 nm to 700 nm.
light lie?
,Describe the motion of The direction of vibrations are perpendicular to the direction of
transverse waves energy propagation.
E.g., a seagull bobbing up and down in water.
What type of waves cannot ● Longitudinal waves.
be polarised and why? ● As their oscillations always occur in one direction - in the
direction of the way - so there's no need to distinguish
between 'different' oscillation directions as there's only one.
What is unpolarised light? A mixture of waves oscillating in different planes.
How can you make a wave ● By passing it through a polaroid filter WHICH ALLOWS waves
polarised, what does this do, oscillating in one plane to pass LOWERING the new wave's
and how does it work? intensity.
● Oscillations in the other directions are absorbed by the
molecules.
Give a use of polaroid filters Light is reflected from the road surface is partially plane polarised.
Polaroid sunglasses can stop the horizontally polarised light getting in
your eyes.
Describe the motion of The direction of vibrations are parallel to the direction of energy
longitudinal waves propagation.
, How is polarisation used in ● TV signal transmitted horizontally or vertically and your
transmission and reception? antenna should match the signal polarisation.
● Antenna in a given area have the same polarisation to
prevent interference from nearby stations.
How does changing the ● Increasing the amplitude makes particles vibrate further
amplitude and wavelength from rest position.
affect particles on a ● Increasing the wavelength increases the distance between
longitudinal wave? consecutive areas of compression/rarefaction.
What ‘in phase’ and ‘in ● In phase: peaks line up with peaks and troughs with troughs.
antiphase’ mean? ● In antiphase: peaks line up with troughs and vice versa.
When are two waves When the phase difference between them is constant. This means
coherent and what does this they have the same frequency.
also mean?
What is amplitude? MAXIMUM displacement from rest position.
What is frequency (in terms The number of waves passing through a point each second
of waves)? (measured in Hz or s-1).
What is wavelength? The distance between two identical consecutive points.
What is time period? The time taken for one complete wavelength to pass a point.
What are mechanical waves Waves that rely on a medium to travel through (e.g., sound waves
(with examples)? and seismic waves).
What are electromagnetic
waves?
Oscillating electric and magnetic fields that are in phase and
perpendicular to one another.
Give 3 properties of ● Can travel through a vacuum.
electromagnetic waves ● Travel at the speed of light (through a vacuum).
● Are all transverse.
What are the sections of the
electromagnetic spectrum Name Properties
and the properties of either
side? Radio Longest wavelength ⇒ lowest frequency ⇒ least
penetrating.
Microwaves, Infrared, Visible, Ultraviolet, X-ray
Gamma Shortest wavelength ⇒ highest frequency ⇒ most
penetrating.
In what range does visible 400 nm to 700 nm.
light lie?
,Describe the motion of The direction of vibrations are perpendicular to the direction of
transverse waves energy propagation.
E.g., a seagull bobbing up and down in water.
What type of waves cannot ● Longitudinal waves.
be polarised and why? ● As their oscillations always occur in one direction - in the
direction of the way - so there's no need to distinguish
between 'different' oscillation directions as there's only one.
What is unpolarised light? A mixture of waves oscillating in different planes.
How can you make a wave ● By passing it through a polaroid filter WHICH ALLOWS waves
polarised, what does this do, oscillating in one plane to pass LOWERING the new wave's
and how does it work? intensity.
● Oscillations in the other directions are absorbed by the
molecules.
Give a use of polaroid filters Light is reflected from the road surface is partially plane polarised.
Polaroid sunglasses can stop the horizontally polarised light getting in
your eyes.
Describe the motion of The direction of vibrations are parallel to the direction of energy
longitudinal waves propagation.
, How is polarisation used in ● TV signal transmitted horizontally or vertically and your
transmission and reception? antenna should match the signal polarisation.
● Antenna in a given area have the same polarisation to
prevent interference from nearby stations.
How does changing the ● Increasing the amplitude makes particles vibrate further
amplitude and wavelength from rest position.
affect particles on a ● Increasing the wavelength increases the distance between
longitudinal wave? consecutive areas of compression/rarefaction.
What ‘in phase’ and ‘in ● In phase: peaks line up with peaks and troughs with troughs.
antiphase’ mean? ● In antiphase: peaks line up with troughs and vice versa.
When are two waves When the phase difference between them is constant. This means
coherent and what does this they have the same frequency.
also mean?
