P13 - Electromagnetic Waves 2️⃣✅ Flashcards
What are carrier waves?
Waves used to carry any type of signal
What is a contrast medium?
Am X-ray absorbing substance used to fill a body organ so the organ can be seen on a radiograph (X-ray)
What is the electromagnetic spectrum?
The continuous spectrum of electromagnetic waves
What is ionisation?
Any process in which atoms become charged
What are microwaves?
Electromagnetic waves between infared radiationa dn radio waves in the electromagnetic spectrum
What is optical fibre?
Thin glass fibre used to transmit light signals
What is radiation dose?
The ammount of ionising radiation a person recieves
What are radio waves?
Electromagnetic waves with wavelengths greater than 0.10m
What is ultraviolet radiation (UV)?
Electromagnetic waves between visivble light and X-rays in the electromagnetic spectrum
What is wave speed?
The distance travelled per second by a wave crest or trough
What is white light?
Light than includes all the colours of the spectrum
What is absorption?
The transfer of energy from teh wave to the medium - when something goes in but doesnt come out
What is transmission?
When something enters another mediunm and still comes out the other side - it isnt absorbed
What waves have ionising power on the electromagnetic spectrum?
UV, X-rays & Gamma rays have the ability to knock off electrons from atoms which can be dangerous in your cells, specifically DNA
Frequency of waves ________________ the electromagentic spectrum
increase up
Wavelength of waves ________________ the electromagnetic spectrum
decrease up
What is the equation for wavespeed?
V = f x λ
wavespeed = frequency x wavelength
What are the 4 ways heat is transferred?
- Coduction
- Convection
- Radiation
- Evapouration
What is black body radiation?
Black bodies are perfect absorbers & emitters of radiation thereofore black bodies neither relfect or transmit & all wavelengths are absorbed
What is the ionosphere?
A layer of ions in our atmosphere. Radiowaves are reflected by the ionosphere
What colour has the largest wavelength?
Red
What colour has the smallest wavelength?
Violet
What colour has the lowest frequency?
Red
What colour has the highest frequency?
Violet
What things can be transported by an optical fibre?
light or infared waves
What is a full-duplex system?
A method of transmitting data in both directions simultaneously, over separate communication lines - allowing 1 person to speak whilst also hearing the other person at the same time
What is a half-duplex system?
Where signals/ data can be both sent and recieived but not both at the same time
What is an example of a device that uses full-duplex systems?
A mobile phone
What is an example of a device that uses half-duplex systems?
A walkie-talkie
How do optical fibres work?
The rays are internally reflected all the way along, inside, the glass tube
As no light escapes optical fibres, does that mean they go on forever?
No, as they are made up of glass and glass absorbs a small ammount of light every time it hits it, the signal would eventually run out
How does a radio station actually work? Put these tabs into the correct order
- 5
- 3
- 2
- 4
- 1
What is radiotherapy?
A type of cancer treatment that uses beams of intense energy to kill cancer cells
What are medical tracers?
Radioactive sources that emitt gamma rays that easily pass through the body to a detector outside the body
Why do medical tracers have to have a short half life?
So it ‘traces’ and does its job and then dies so it causes minimal damage to your body cells
What is dose?
The ammount of damage that would be caused by the absorption of 1 joule of energy in each kg of body mass
What are the units to measure radiation dose?
Sieverts, Sv
What is a dosimeter?
A machine that measures the dosage of radiation
What is a CT scan?
A medical imaging technique that is used to obtain detailed images of the body.
What does CT scan stand for?
Computed Tomography Scan
How do X-rays work?
- X-rays are fired at the limb/ object that is ontop of photographic film
- X-rays pass through soft tissue, therefore hitting the photographic film, turining it black
- X-rays are absorbed by teeth, bones and metal objects, therefore not reaching the photographic film, leaving it white
How does photographic film work?
- When hit by an X-ray it turns black
- When not hit by X-ray it remains white
What does a contrast medium allow X-rays to do?
View soft tissue
How do contrast mediums work?
Contrast medium are digestible substances that absorb X-rays more easily - therefore leaving the organ the contrast medium is inside white on photographic film as no X-rays passed through it and reached the film, they were absorbed, leavining the once black soft tissue/ organ white on an X-ray
What do doctors use X-rays for?
Commonly for viewing breaks or fractures in bones & sometmes teeth. Can sometimes be used to view soft tissue & organs when used along side a contrast medium
What do doctors use CT scans for?
Diagnose tumours, investigate internal bleeding or to check for other internal damage
What is the mneumonic to remeber the order of the electromagnetic spectrum?
R aging
M artians
I nvade
V enus
U sing
X -ray
G uns
Using the mneumonic for the electromagnetic spectrum, list the electromagnetic spectrum in order.
- Radio waves
- Microwaves
- Infared
- Visible
- Ultraviolet
- X-ray
- Gamma
What is one hazard of exposure to UV light?
- skin cancer
What is the range of wavelengths in the electromagnetic spectrum?
What type of camera uses infared radiation to form images?
A thermal imaging camera
What 2 types of electromagnetic waves are used when cooking food?
Microwaves (microwave oven) and infared to heat things up
What type of scan would a pregnant woman have and why?
Ultrasound because they use sound waves and are not ionising like x-rays
What is a Charge Coupled Device (CCD)?
A charged coupled device (CCD) absorbs infrared radiation to produce an image. Each pixel in the CCD detects the infrared radiation and the data can be processed using a computer.
What are uses for each type of electromagnetic radiation?
