(c) the electromagnetic spectrum

electromagnetic spectrum in decreasing wavelength order (3.10 / 3.11)

radio waves

microwaves

infrared light

visible light (red, orange, yellow, green, blue, indigo, violet)

ultraviolet light

x-rays

gamma rays

these all travel at the same speed in free space (3 × 10⁸ m/s)

radio waves (3.12 / 3.13)

uses:

• radio broadcasts

• television signal transmissions

• international phone call transmissions

dangers:

• none

detector: aerial and electronic unit

wavelength: from 10³m - 10⁰m

microwaves (3.12 / 3.13)

uses:

• satellite transmissions

• cooking (such as with microwave ovens)

dangers:

• internal heating of body tissue if subject to prolonged exposure

• so don’t prolongingly expose yourself to microwaves

detector: aerial and electronic unit

wavelength: around 10^-2m

infrared light (3.12 / 3.13)

uses:

• anything warmer than its surroundings will transfer energy by giving out infrared radiation → used for heaters and night vision equipment

dangers:

• skin burns

• so keep out of the sun, wear protective clothing

detector: electronic detectors, special photographic film

wavelength: around 10^-4m

visible light (3.12 / 3.13)

uses:

• seeing with your eyes :O

• transmitting information along optical fibres

• taking photographs

dangers:

• if very bright, light can damage the eye

• so don’t look directly into the sun or at least wear sunglasses

detector: eye, photographic film, electronic devices

wavelength: around 10^-6m

ultraviolet light (3.12 / 3.13)

uses:

• energy-efficient lamps

• detecting bank note forgery

• killing bacteria

dangers:

• prolonged exposure can cause skin damage

• so don’t stay in the sun for too long, wear protective clothing and wear your sunscreen!!!!! skin cancer is not sexy🙅‍♀🙅‍♀🙅‍♀🙅‍♀🙅‍♀🙅‍♀🙅‍♀🙅‍♀

detector: photographic film

wavelength: around 10^-8m

x-rays (3.12 / 3.13)

uses:

• x-rays of short wavelengths will pass through body tissues but will be absorbed by bone

• x-rays of slightly longer wavelengths are used in body scanning. these waves are absorbed to different degrees by body tissues so doctors can build a picture of inside a patient’s body

dangers:

• can cause damage to your body tissues

• so exposure should be as limited as possible

detector: photographic film

wavelength: around 10^-10m

gamma rays (3.12 / 3.13)

uses:

• medical tracers

• concentrating them towards cancerous cells to kill them

• sterilisation

dangers:

• cell destruction

• cell mutation

• cancer

detector: photographic film, GM tube

wavelength: around 10^-12m