similarities of electromagnetic waves
- they can all travel through a vacuum
- they ALL travel at the same speed in a vacuum
- they are transverse waves
uses of radio waves
- broadcasting ( radio and TV)
- MRI-magnetic resonance imaging
uses of X rays and γ rays
- sterilisation
- medical imaging
- medical treatment
uses of ultraviolet
- sterilisation
- sun tanning
- fluorescent lamps
uses of visible light
- optical fibres
- photography
uses of infrared
- night vision goggles+cameras
- remote controls
- cooking
uses of microwaves
- radar
- telecommunications (mobile phones)
- cooking
Wavelength range (m) of radio waves
> 10^6 to 10^-1
Wavelength range (m) of micro waves
10^-1 to 10^-3
Wavelength range of γ rays
10^-10 to 10^-16
Wavelength range of visible light
7 × 10^-7 RED to 4 × 10^-7 VIOLET
Wavelength range of X rays
10^-8 to 10^-13
Wavelength range of ultraviolet
4 × 10^-7 to 10^-8
Wavelength range of infrared
10^-3 to 7 × 10^-7
Ultraviolet (UV-A, UV-B, UV-C)
- The Ultraviolet (UV) band of the EM spectrum is split into 3 subdivisions.
- Sun produces all 3
- Almost 99% of UV at sea level is UV-A
Positive effects of ultraviolet
We need some sunlight as UV-B in sunlight acts on skin to produce vitamin D
Negative effects of ultraviolet
- UV-A is v.penetrating and therefore causes wrinkles
- UV-B can damage DNA in skin cells and so lead to cancer
- All UV can damage the eyes
Wavelengths of the different types of UV light (nm)
UV-A: 400-320
UV-B: 320-280
UV-C: 280
Purpose of sunscreen
sunscreen absorbs UV as it contains substances like titanium dioxide that absorb UV
Who is really smelly
gregory
Who is smellier
Ifor
who is the smelliest
gregory
Who is really silly
Both Gregory and Ifor
