P8: Electromagnetic Waves Flashcards
Electromagnetic Spectrum
Smallest - Largest: Gamma X-ray Ultraviolet Visible Infrared Micro Radio
Units of electromagnetic wave measurement from smallest to largest
Picometre
Nanometre
Millimetre
Kilometre
How fast do electromagnetic waves travel in a vacuum?
300 million m/s
White Light
Light from ordinary lamps and the sun
The hotter an object is…
… The more infrared radiation it emits.
How does infrared radiation affect the body?
It can damage or kill skin cells by heating them up.
Optical fibres
The glass fibre used to send light signals along.
Uses infrared radiation.
4 uses of infrared radiation
Optical fibres
remote control handsets
infrared scanners
infrared handsets
The shorter the length of radio waves:
The more information they can carry.
The shorter their range.
The less they spread out.
What are microwaves used for?
Satellite phones
TV links
Satellite TV
(Can travel between satellites, don’t spread out much so the signal doesn’t weaken as much.)
What are radio waves
TV broadcasting (Can carry more information than longer radio waves)
What are radio waves >1m used for?
Local Radio Stations
Have limited range
What are radio waves >100m used for?
National and International Radio Stations
Very large range
What do electromagnetic waves carry?
Information
What effect does UV radiation have?
It is harmful to human eyes and can cause blindness.
What produces gamma rays?
Radioactive substances when unstable nuclei release energy.
What produces x rays?
When particles moving at high speeds are stopped.
Which are more penetrative: X or Gamma rays?
Gamma, they have shorter wavelengths.
Applications of X-Rays
X- Rays
To detect internal cracks in metal
3 Uses of Gamma Radiation
> Killing bacteria in food
Sterilising surgical equipment
Killing cancer cells.
Safety concern of X-Ray and Gamma
Causes ionisation, which can result in cell mutation and death.
How an X-Ray works
- X-Rays from an X-Ray tube are directed at the patient. A lightproof cassette is placed in the other side of the patient.
- X-Rays pass through soft tissue, but are absorbed by bones, teeth and metal.
- Where the X-Rays reach the flat-panel detector inside the lightproof cassette it turns darker and creates a clear impression of the bones etc.
How to get an X-Ray of an organ.
Give the patient a contrast medium that absorbs x-rays before their scan.
Flat Panel Detector.
A small screen that contains a CCD (charge coupled detector), which converts X-Rays to light. The light creates electronic signals which are sent to a computer.
CT scanner
Uses X-rays to produce a digital image of any cross section in the body or a three-dimensional image of the body.
