(3.10-3.13) EM spectrum- features, uses and dangers

What is the electromagnetic spectrum?

Transverse waves that travel at the same speed through a vacuum.

Made up of 7 types of waves, grouped depending on their wavelength.

List the waves in the EM spectrum.

Gamma

X-rays

Ultra-violet

Visible

Infrared

Micro-waves

Radio waves

From radio to gamma, what happens to the wavelength and frequency?

λ- get shorter

f- gets higher

What is the relationship between f and λ?

Inversely proportional

What are the colours of visible light in order of decreasing wavelength?

Red

Orange

Yellow

Green

Blue

Indigo

Violet

What are radio waves used for?

broadcasting + communications

What are micro-waves used for?

cooking- at high intensities

satellite transmissions

What is infrared used for?

heaters

night vision equipment

IR is given out by all objects- the hotter the object, the more IR

What is visible light used for?

optical fibres

photography

What is UV light used for?

fluorescent lamps

What are x-rays used for?

observing the internal structure of objects and materials- medicinal

creates a negative image by travelling through flesh but being absorbed by bones

What are gamma rays used for?

sterilisation by killing microbes-

• food, equipment

What is the danger of EM waves?

Overexposure of the human body to EM waves can be detrimental.

Why are shorter wavelengths more dangerous?

frequency of a wave increases = energy increases

energy becomes high enough to ionise atoms

shorter wavelength = more ionising power

What are the risks of micro-waves and how are they protected against?

heating of internal body tissue

• preventing from escaping microwaves by shielding

What are the risks of infrared and how are they protected against?

skin burns due to heating effect

• wearing protective, insulating clothing

What are the risks of UV light and how is it protected against?

damage to surface cells

blindness

can cause mutation - cancer

• sunglasses shield eyes

• sunscreen prevents damage

What are the risks of x-rays/gamma rays and how are they protected against?

cancer

mutation

• minimal exposure

• shielding equipment

• radiation badges to measure levels

• routine tests for those working with them