Studied by 1 person
equation for frequency
frequency= 1/time period
equation for time period
time period= 1/frequency
equation for wavespeed
wave speed= frequency x wavelength
wave definition
a repeating, periodic motion resulting in the vibration of particles or changes in electromagnetic fields
what do waves do
transfer energy from one place to another, but don’t transfer any matter
wavelength definition
distance between corresponding points on adjacent waves (e.g. peak to peak or compression to compression)
what is wavelength measured in
metres
amplitude definiton
maximum displacement of the wave from its equilibrium position (distance from the centre to its peak)
what is amplitude measured in
metres
time period definition
the time it takes for one complete oscillation
frequency definition
the number of complete oscillations per second
what is frequency measured in
Hertz (Hz)
what is wave speed measured in
m/s
what two factors of waves are inversely proportional
frequency and wavelength
what are the two types of waves
transverse
longitudinal
what is a transverse wave
a wave where its particles oscillate perpendicular to the direction of energy transfer
what are the parts of a transverse wave called
peaks and troughs
what is a peak
top of the wave
what is a trough
bottom of the wave
examples of transverse waves
water waves
seismic S waves
all electromagnetic waves
what are longitudinal waves
waves where the particles oscillate parallel to the direction of energy transfer
how do longitudinal waves form
varying amounts of pressure between particles
what are the different parts of a longitudinal wave
compressions and rarefactions
what is a compression
close together
what is a rarefaction
far apart
examples of longitudinal waves
sound waves
seismic P waves
what can waves do when they reach a boundary
reflect
refract/transmit
absorb
diffract
what is absorption of a wave
the wave energy transfers into the objects energy stores
what is transmission of a wave
aka refraction; where the wave passes through and then out the other side
what is reflection
where the wave reaches a boundary and is bounced off the surface, without penetrating the substance
factors that affect what a wave does when it reaches the surface
wavelength
properties of the two substances
how can you show reflection taking place
ray diagrams
rule of angles during reflection
angle of incidence=angle of reflection
how to draw a ray diagram
draw boundary at the bottom
draw incoming ray of light; draw arrow showing that it is going towards the substance
draw the normal line
measure the angle of incidence
as angle of incidence=angle of reflection, the angle of reflection away from the surface is the same as that of the angle of incidence previously drawn so draw the angle of reflection at the same angle leaving the surface
what is the boundary line
a straight line representing where the two substances meet
e.g. air and the surface of a mirror
what is the normal line
a dashed line perpendicular to the boundary line
what is the angle of incidence
the angle between the incoming ray and the normal line
what is the point of incidence
the point where the incoming ray meets the surface
what are the two types of reflection
specular reflection
diffuse/scattered reflection
what is specular reflection
where the boundary is flat (e.g. surface of a mirror) so all of the normal lines are in the same direction and therefore all the incoming rays are reflected out at the same angle
what is the image with specular reflection like
clear image
what is diffuse/scattered reflection
when the surface of the boundary is bumpy/rough meaning that although all incoming rays come at the same angle, the normal lines are all at different angles, so the incoming rays are reflected at different angles
can we see ourselves in materials with diffuse/scattered reflection
cannot see ourselves at all
what is refraction
when waves change direction as they pass from one medium to another
why do waves travel at different speeds in different mediums
different mediums have different densities
does a wave go faster or slower with a higher density
slower
what happens if a wave hits a new medium at perpendicular
it will travel straight through the medium, just at a faster/slower rate
what happens if a wave hits a new material at an angle
the wave will be refracted and its direction changes
which way will a wave refract if it travels into a more dense medium
it will refract towards the normal line
how to draw a ray diagram
draw material that the incident ray is going into
draw incident ray at angle toward medium
draw normal line, perpendicular at the point of incidence
draw the refracted ray and continue this all the way to the other side of medium
draw new normal at point the refracted ray leaves the medium
as refracted ray travelling from more dense to less dense medium, it then refracts away from the normal line
add angle of incidence
add angle of refraction
what is the incident ray
the ray that enters the medium
what is the point of incidence
where the incident ray hits the new medium
what is the name of the ray that leaves the medium
emergent ray
what is the angle of incidence
the angle between the normal line and the incident ray
what is the angle of refraction
the angle between the new normal line and the refracted ray
what does it mean for the wavelength of the wave if its speed changes through the medium
it increases/decreases depending on new speed
if speed increases the wavelength increases and vice versa
does the frequency change during refraction
no
what happens if a white light was shone through a triangular prism
all of the different colours of light that make up the white light refract different amounts so a rainbow appears
when does total internal reflection occur
when the angle of incidence when being refracted is too big
what is TIR
when light reflects within a block and the Law of Reflection applies instead
what is the critical angle
the minimum angle at which TIR will occur and refraction no longer occurs
what happens to the size of the critical angle if the refractive index is larger
smaller critical angle
what appliances use TIR
bike reflector
cats eyes
optical fibres
what are optical fibres
thin, flexible, transparent fibres that light can pass through via TIR
what are optical fibres used for
decoration
communications
when does diffraction occur
when waves pass around a barrier
why do waves redirect slightly
to fill the shadow zone
what is the shadow zone
the space behind the barrier
example of diffraction
radio waves diffract around a mountain so the house receives a signal
when does interference occur
when two waves from separate sources come together
what is constructive interference
when two peaks/trough combine
what is destructive interference
peak and trough combine
what is the electromagnetic spectrum
a group of waves that all travel at the speed of light in a vacuum
how are electromagnetic waves created
by changes in electric and magnetic fields
do electromagnetic waves transfer energy using particles
no
what type of wave are electromagnetic waves
transverse
what wave behaviour can electromagnetic waves have
reflect
refract
diffract
absorb
transmit
what are the electromagnetic waves
radio waves
microwaves
infrared
visible light
UV
x-rays
gamma
what differentiates the different electromagnetic waves
wavelength
frequency
how are frequency and wavelength related in electromagnetic waves
inversely proportional
which EM wave has the longest wavelength
radio waves
which EM wave has the shortest wavelength
gamma
which EM wave has the highest frequency
gamma
which EM wave has the lowest frequency
radiowaves
what is the only pat of the EM spectrum that humans can detect
visible light
how can radio waves be generated
through electricity with alternating current
equipment used to generate radiowaves
transmitter connected to an oscilloscope
what does an oscilloscope do
allows us to see the frequency of alternating current
why is the frequency of the alternating current important
determines the frequency of the EM wave
what object receives the transmitted radio waves
receiver connected to an oscilloscope
use of radio waves
communication
what are the three types of radio wave
long wave
short wave
very short wave
what distance can long waves be transmitted
very long without having to interact with anything along the way
how do long waves transmit very long distances
they diffract around the curved surface of the Earth
what distance do short waves transmit
long distances still but cannot curve around the surface of the Earth
also short distances e.g. bluetooth
how are short waves transmitted
reflected by ionosphere in atmosphere and then bounce back and forth to cover long distances
what are very short waves used for
TV and FM radio
how do very short waves travel
directly from receiver to transmitter
are there any dangers of radio waves
no
what are the two types of signals
analogue
digital
