Electromagnetic waves Flashcards
What his the Order of radiation from long to short
Radioactive
Microwave
Infrared
Visible
Ultra violet
X-ray
Gamma ray
What is the speed of light
3 x (10 x 8)
Which radiation has the highest energy and why
Gamma rays because it is highly penetrable and ionising
What is ionising wave
It can remove an electron from an atom
What does it mean if a radiation has high energy
It is easy for the waves to penetrate matter rather than being absorbed
However the higher the energy the more damage caused by radiation
What is absorbtion
Transfer of energy from the wave to the medium (light and a curtain-medium)
What is white light
Visible light from the sun or a regular lamp
What is an endoscope
It is a medical equipment that contains 2 bundles of fibre. One set of fibres transmits light into a body cavity and the other is used to return an image inside the cavity
What are radio waves used for
To carry to and mobile signals
Bluetooth enables devices to use low powered radio waves to communicate and transfer wireless signal
What is the ionosphere
The part of the atmosphere that is ionised by solar radiation
Why are radio waves reflected by the ionosphere
Because it can not penetrate the ionosphere but microwaves can
How do microwaves heat food
They penetrate the food and are absorbed by the water and fat molecules which cause them to vibrate and emit IR radiation thus heating up
What are example of where infrared radiaton
Optical fibres
Communication systems
Infrared cameras
Infrared scanners
How is infrared radiation used for communication
Equipment transmits signals through sending and receiving impulses of IR radiation
What can infrared scanners be used for
To detect IR emitted from hotspots in the bidy
Give an example of communication with infrared and microwave radiation
IR - remote control
Micro- cell phones
State 2 properties that are the same for microwaves and IR
they both travel at the same speed
They are transverse waves
What is the range of wavelengths od electromagnetic waves
10 to the power of - 15
To 10 to the power of 4
What is a black body radiation
They are objects that are completely black and are perfect absorbers and emitters of radiation, none is reflected or transmitted
What type of waves are electromagnetic waves
Transverse
How are electromagnetic waves grouped in the electromagnetic spectrum
Terms of the frequency and wavelength
How do radio waves generate electric currents
They transfer energy to the kinetic energy source of electrons in radio receivers
What are electromagnetic waves vibrations off
Electric and magnetic field
Why can electromagnetic waves travel in a vacuum
Because they are vibrations of electric and magnetic field not particles
How do you draw ray diagrams
Start by drawing the boundary line between your two materials (horizontal)
Then draw the normal which is an imaginary line that is perpendicular to where the the incoming wave hits the boundary.
Draw an Incident ray that meets the normal at the boundary (where the wave hits the boundary.
The angle between the incident ray and the normal is the angle of incidence.
Then draw the refracted ray opposite to the incident ray
The angle of refraction is between the refracted ray and the normal.
How are electromagnetic waves produce
Alternating currents made up of oscillating charges and as the charges oscillate they produce oscillating electric and magnetic field
What happens to the light as it passes from the surroundings to the glasses
Turn off the light is reflected back and some of the light transmit through
Explain how a light rays speed and direction change when passing through glass into a vacuum
It will speed up and bend away from the normal
What happens when radio waves are absorbed
They may create an alternating current with the same frequency is the radio wave itself therefore they can induce oscillations in electrical circuits
How are electromagnetic waves generated
By changes in atoms and the nuclei of atoms
What does the effect of hazardous raise on human body tissue depend on
The dose And the type of electromagnetic wave
What is radiation dose
The measure of the risk of harm resulting from an exposure of the body to the radiation
How many milli sievert are in one Sievert
1000
What is a Leslie cube
A hollow water type metal cube made of aluminium with four vertical faces that have different surfaces
Describe an experiment with infrared radiation
Hey some empty Leslie cube on heatproof mat
Then boil water in a castle and feel the Leslie here with the water
Wait for a few minutes for the kids to warm up then hold a thermometer against each of the faces all four should have the same temperature
Then hold an infrared detector at a distance away from one of the faces and record the IR radiation
Then repeat this for each of the faces with the infrared radiation detector at the same distance.
Describe the result of the Leslie cube experiment
There should be more infrared radiation from the black surface than the white one and more from the mat surfaces from the shiny ones
What happens when an object absorbs microwaves
It will become hot
What should scientist do to find out whether phones affect health
Compare the health of non mobile users
With mobile users
Infrared radiation is passed through glass. 70 per cent is transmitted and 5 percent is reflect how much is absorbed
25 percent
What happens when a metal Ariel absorbs radio waves
It creates an alternating current with the same frequancy as the wave causing it to heat up
Why can we assume that visible light and microwaves travel at the same speed
All EM waves travel at the same speed in a vacuum
Which object has the greatest rate of energy transfer in order from best to least and why:
Start temp. Finish temp
A. 70. 5
B. 80. 0
C. 90. 30
B A C
Biggest temp diff
Which can with boiling water will get to room temp faster
Dark Matt
Dark shiny
Light Matt
Light shiny
Dark Matt because it is the best absorber
