P13- Electromagnetic waves Flashcards
Electromagnetic waves 4 properties?
Transverse waves
Transfer energy
Travel through a vacuum
All travel at same speed (speed of light)
Electromagnetic waves fact about frequency and wavelength?
As they all travel at the same speed,
-if frequency increases, wavelength decreases
-if frequency decreases, wavelength increases
Order of electromagnetic spectrum and pneumonic?
Gamma ray-> X ray-> Ultraviolet-> Visible-> Infrared-> Microwave-> Radio
Gammon x-rays use vibrant red micro radios
Which electromagnetic waves have shorter wavelengths?
Their frequency, energy, danger and penetrating?
Gamma and X-rays.
Shorter wavelength
Higher frequency
Higher energy
More dangerous
More penetrating
White light
Type of wave?
Found in?
Contains?
How to see it?
Electromagnetic
Sunlight
All the colours of the visible spectrum
Rainbow or glass prism
Dif between colours of light?
From violet to red it..?
Different wavelengths /frequencies
Wavelength increases
Absorption and emission of infrared radiation practical
Fill a shiny silver can and a matte black can with 200ml water straight from kettle and add a lid. Record initial temp and start the stopwatch. Record the temp of water every minute. After 5 mins calculate the total temp change. The silver can should have the least change due to radiation back into the water.
Radio waves
Uses?
Dangers?
Radio, TV, mobile phone
Can cause internal heating in the body
Microwave
Uses?
Dangers?
Heat up food, satellite signals
Can be absorbed by body cells
Infrared waves
Uses?
Dangers?
Remote control for TV, electric heaters
Eye damage form bright light
Visible waves
Uses?
Dangers?
Cameras to take photos
Eye damage from bright light
Ultraviolet waves
Uses?
Dangers?
Sunbeds, sterilise medical equipment
Skin cancer, blindness
X rays
Uses?
Dangers?
Identify broken bones, kill cancerous cells
High dose can kill living body cells
Gamma rays
Uses?
Dangers?
Kill bacteria in food, sterilise medical equipment
High does can kill living body cells
Infrared radiation
Emitted by?
Heat affecting the amount emitted?
Effect on the body?
All objects
Hotter the object, more infrared radiation it emits
Absorbed by the skin, can damage body cells
Carrier waves
Waves used to carry any type of signal
How are radio waves divided?
What 3 things does this affect?
Into groups based on their wavelength and frequencies.
How far they travel, how much they spread, how much info they carry
Shorter radio wavelengths..
Info?
Range?
Spread out?
More info
Shorter distance travelled
Spread out less
Shorter radio waves used for and why?
Longer radio waves used for and why?
Even longer radio waves used for and why?
Tv signals-> carry more info
Local radio stations-> greater range, not huge
National radio stations-> large range
Shorter radio wavelengths around Earth?
Larger radio wavelengths around Earth?
Reflect of the outer atmosphere of Earth (ionosphere)
Diffract (bend) around Earth
Mobile phones
Emits?
Causes?
Radio signals
May affect the brain when close, need more research
How are signals transmitted and detected?
Transmitter: Produces alternating current, causes electrons to oscillate, produces carrier waves
Receiver: Carrier waves absorbed by electrons in antenna, causes them to oscillate, produces alternating current at same frequency as carrier waves produced from transmitter.
Optical fibres
Transport?
Use?
Key feature?
How are the waves reflected and what is it called?
Signals, light or infrared radiation
Flexible
Visible light/infrared reflects off the inside of the optical fibre and
cannot escape.
Total internal reflection.
Optical fibres
Info?
Security?
Carry more info than radio or microwaves, due to shorter wavelengths
More secure as signals stay in the fibre
Ionisation
The process of making uncharged atoms become ions
2 Types of EM waves that cause ionisation and how?
Gamma and X-rays
As they pass through substances, can knock electrons out of atoms so they become charged
Ionisation effect on living cells?
Can cause the cell to die or mutate
3 Effects of lower doses of ionisation in humans
Radiation can ionise DNA, which damages it
Can cause mutations
Can make cells reproduce rapidly (i.e. cancer)
3 Effects of higher doses of ionisation in humans
Radiation can ionise DNA, which leads to cell death
Can then cause radiation burns or sickness
Very useful if want to kill the cell e.g. radiotherapy
3 Ways for people working with X-rays to be protected?
Film badge which monitors level of radiation
Lead apron
Standing behind a screen
How do X-ray machines work?
Dark and light areas?
X-ray machine produces x-rays at patient. Flat-panel detector placed beneath patient.
Rays pass through softer parts like tissue, show up as darker areas. Rays are absorbed by denser parts like bones, show up as lighter areas.
What is a flat-panel detector and what does it do?
A small screen that contains a charge-coupled device (CCD). This converts X-rays to light, so a computer to display a X-ray image
How to see an organ on an X-ray?
Use a contrast medium in the organ, eg eating a substance that absorbs X-rays to see the inside of a stomach
3 things that affect the radiation dose?
What is it measured in?
Type of radiation
Length of exposure
Rate of absorption from body
Sieverts (Sv)
