P13 Flashcards
What are EM waves?
Transverse waves that transfer energy from a source to an absorber.
Whats an example of am EM wave?
Hot object transferes energy by emitting infrared radiation which is absorbed by the air.
What do all EM waves travel at?
The same speed through air or a vaccum
Radio waves wave length?
1m - 10^4m
Micro waves wavelength?
10^-2m
Infra red wavelength?
10^-5m
Visible light wave length?
10^-7m
Ultra violet wave length?
10^-8m
X-rays wave length?
10^-10
Gamma rays wave length?
10^-15
Why is there a large range of frequencies?
Because EM waves generate by a variety of changes in atoms and their nuclei
What do human eyes detect?
Visible light
How are radio waves made?
Oscillating charges
What happens when radio waves are absorbed?
They create alternating currents with the same frequency as the radio wave itself
What can changes in atoms and nuclei result to?
EM waves generated or absorbed over a wide frequency range
Where do gamma rays originate from?
Changes in nucleus of an atom
What effects do UV, Xrays and gamma rays have on the human body?
Effect human body tissue
What is radiation dose?
Is measure of risk exposing the body to radiation
100msv =
1Sv
What can UV increase?
- Skin age to increase
- Skin cancer
Uses of radio waves?
Television and radio
Uses of microwaves?
Satelite communication and cooking food
Use of infrared
Electrical heaters, cooking food,infrared cameras
Uses of visible light?
Fibre optic communications
