P5.2 Electormagentic Spectrum Flashcards
What are the facts about electromagnetic radiation?
(Need particles? Speed in air? Transverse? What do they do?)
What is the spectrum (Acronym too?)
Which one can we see
- EM waves are transverse waves
- they’re are vibrations of electric and magnetic fields, so they din’t need particles to vibrate, meaning they can travel through a VACUUM
- THE SPEED IS THE SAME IN AIR OR VACUUM, but change in different materials
- organised into 7 , with highest wavelength to lowest wavelength
- because v= lamda F. The wavelength highest will have lowest frequency
- RMIVUXGAM
- Radio highest wavelength lowest frequency, micro, Indra Fred, visible light, ultra violet, x ray gamma
Alternatively remember Radio highest, gamma lowest. Visible in middle, and Infra left ultra violet right (because of rainbow). Fill it in between
What about visible light?
What do waves with higher frequency do?
Therefore which most damaging.
Visible light is also organised into wavelengths, from long to short red orange yellow green blue indigo violet
- HIGHEST FREQUENCY TRANSFERS MOST ENERGY. THEREFORE, GAMMA THE MOSR DAMAGAIN RAYS…
More on em for fun
Where energy transferred
What speed of the em
They are 3 x ton 8 meters, speed of of light because light is part of spectrum
The electric and magnetic oscillate at 90 degrees from the direction of energy transfer, AND each other.
Remember energy transferred from source to absorbers
HOW DO YOU PRODUCE AND DETECT RADIO WAVES?
1) an oscillating old SCROOS a wire, causes electrons to move back and forth, creating a changing magnetic and electric field- an which is emitted as an EM RADIO WAVE.
2) when an aerial receives this radio wave, the changing electric and magnetic fields cause the electrons in the aerial to move back and forth in the same way, producing a signal. This will be the same signal transmitted, depending on the (frequency ). This is how they work.
A.c / alternating pd causes electrons to move at a frequency (charges oscillate), producing em wave, when received by aerial , will cause electrons (charged particles) to move in same way at same frequency, causing a current to be produced,
What are problems with some EM waves?
(Ionising and cataracts?:
- micro and infra red can be absorbed by skin cells, causing them to heat or burn
BUT UV
- Ultraviolet radiation is absorbed by skin, but higher frequency means more energy transferred and more damage, it can damage the DNA in cells of skin, and since cells here divide by mitosis quick, skin cancer can occur. They cause Ionisation in cells- causing damage
- gamma and x rays are also ionising radiations, which can also cause genetic mutations and cancer…, but too even deeper tissues.
- ultraviolet in eyes also causes CATARACTS WHICH MAKE BLURRY.
What are good uses of EM radiation?
Communication, heating, sterilising, , cameras etc
X COMMUNICATION :
- radio waves used to transfer information of sound and colour
- phones use microwaves to communicate , and with satellites in space too (because not absorbed by earth atmospher un like radio)
- Bluetooth uses microwaves too
- infra red is used in remotes to transfer signals
- visible light used by sailors for morse corde or by ships
- HEATING
- microwave ovens use microwaves to transfer energy and heat up food, this happens a few cm in absorbed by water molecules which heat up and conduction heats to centre to centre..
- infrared in grills and ovens heat too
- INFRARED RADIATORS CAN HEAT YOU UP BY TRANSFERRING ENERGY TO YOUR THERMAL STORE…
- CAMERAS
- infrared radiation given off by all objects, more warm, more infrared, and an infra red detecting cameras can produce electric signals and make it a picture…
- DVDs
- use visible light with lasers to store data
- medical
- GAMMA RAYS STERILISE THINGS AS THEY KILL CELLS
- x rays also kill cells, so can be used to treat cancer,
- uv rays also kill bacteria, so can be used to sterilise water…
- IMAGING
- x rays for broken bones.
There are more still
How used in communication?
used to transfer information of sound and colour
- phones use microwaves to communicate , and with satellites in space too (because not absorbed by earth atmospher un like radio)
- Bluetooth uses microwaves too
- infra red is used in remotes to transfer signals
- visible light used by sailors for morse corde or by ships
- radio waves use radio waves sit self
All different wavelengths
Heating
- HEATING
- microwave ovens use microwaves to transfer energy and heat up food, this happens a few cm in absorbed by water molecules which heat up and conduction heats to centre to centre..
- infrared in grills and ovens heat too
- INFRARED RADIATORS CAN HEAT YOU UP BY TRANSFERRING ENERGY TO YOUR THERMAL STORE…
Cameras?
Infrared is given off by everyone so an infrared camera can make models by detecting signals and making a picture
DVDs optic fibre
Use visible light with laser and make infirmatijngo
Also visible light is used optical fibres, carry data over distances as pulses of light (I tenets cables and telephone)
Medical
GAMMA RAYS STERILISE THINGS AS THEY KILL CELLS, and so can be used in cancer treatments
- x rays also kill cells, so can be used to treat cancer,
- uv rays also kill bacteria, so can be used to sterilise water…
Imaging
Infrared ?
His charge coupled devices produce image?
X days?
Infrared cameras can detect infrared radiation and produce image called thermogram , shows different regions of temperatures . Your skin emits more infrared if hot due to injury and infection sot hess can be detected
- pixels inside CHARGE COUPLED DEVICE , such as phone camera, absorbed infrared and produce an image
2) x rays are transmited by soft tissue but absorbed by dense like bones, so can diagnose bone fracture as PHOTOGRAPHIC film darkens when it absorbed x rays (stays white if not) - computers can make 3D images of body (organs = computerised tomography Scans
How are gamma rays used in imaging
Gamma rays are transmitted. T all body so can be detected outside
1) tracers of gamma rays are injected or swallowed, and as they move they emit gamma rays in which a gamma camera detects it and forms an image .
The kidney absorbs
Gamma rays can be used to find leaks, as you find more gamma rays above a leak of a pipe than in the rest of the piepem
Uv rays in fluorescence ?
Flruosxoence did a properere where a substance baskets uv and emits light, good for needing light for long periods like classrooms
Summary?
- communication (radio micro visible light morde code, fibre optic too)
- heating (micro, infrared )
- sterilisation (gamma and uv)
- medical (gamma x used for killing cancer, uv for bacteria)
- DVD’s (visible)
- imaging meidalm(infrared thermogram, x ray and ct, gamma tracers
- uv florusedne too
