P1b Electromagnetic Spectrum

Covers information on all of the different electromagnetic waves and their individual uses.

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  • Created by: Hollie
  • Created on: 21-06-11 22:11

Electromagnetic Spectrum - General

Electromagnetic radiation travels as waves moving energy from place to place

All Electromagnetic waves travel through space (vacuum) at the same speed, approx 300 million m/s

The waves are grouped according to their wavelength and frequency


Wave Speed (m/s) = frequency (hz) x wavelength (m)

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Electromagnetic Spectrum - Gamma

Gamma radiation has the highest frequency and shortest wavelength

It is the most penetrating - cannot be felt or seen

Gamma mainly passes through soft tissue and skin however some can be absorbed by the cells which is very dangerous


  • Sterilising surgical/ medical equipment
  • Killing harmful bacteria in food
  • Killing cancer cells (in too low a dose it can however cause cancer)
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Electromagnetic Spectrum - X Rays

X - rays can be said to be very similiar to gamma radiation

They cannot be seen or felt

X-rays pass through soft tissue however not metal and bone


  • X-ray machines in hospital - looking for broken bones etc
  • Radiographs

When using x-rays, staff must stand behind a lead screen and wear lead aprons to ensure that they are not exposed to the x-rays themselves

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Electromagnetic Spectrum - Ultraviolet

Ultraviolet light is found naturally in sunlight

It cannot be seen or felt by a human, however the effects of ultraviolet can be seen as skin turns brown from exposure to this light.


  • For security pens
  • In sun beds
  • In fluroscent lighst and tubes (reamitted as visible light)

Ultraviolet does however cause a lot of damage to skin cells such as skin cancer, sunburn and skin-ageing. Over exposure can also cause problems with eyesight.

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Electromagnetic Spectrum - Visible Light

This is the only light on the electromagnetic spectrum that is visible to and detected by the human eye

Visible light covers all of the light from red to violet. These different colours can be seen within its different wavelengths


  • Transmitted down optical fibres
  • Anything that uses colour
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Electromagnetic Spectrum - Infra Red

Infra-red radiation is given out by all objects - it is invible radiation

As humans we feel this radiation as heat, the hotter an object the more infra-red radiation given out

Infra red radiation is absorbed by the skin and can cause burns


  • Heat source for toasters, grills and heaters
  • Night vision equipment (detects heat)
  • Optical fibre communication
  •  TV, radio and various other controls
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Electromagnetic Spectrum - Microwaves

Microwaves produce frequencies that are absorbed by water molecules in food, heating food from the inside out

Microwaves cannot be seen however they can damage/kill living cells from the heat and water released

The wavelengths produced are able to pass through the atmosphere


  • Transmit mobile phone signals/communication
  • Heat food
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Electromagnetic Spectrum - Radiowaves

Radiowaves have the longest wavelength and lowest frequency

It works with an alternating current/voltage

When an alternating voltage is applied to an aerial, radio waves are emitted with the same frequency


  • Transmit TV signal
  • Transmit radio programmes
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Analogue & Digital Signals

Analogue and digital are the two types of communication signal

Analogue - varies continuously in amplitude


Digital - Only has certain values of 1 (on) and 0 (off)


When signals are transmitted they become less strong and have to be amplified to make them louder, however this also makes any 'pick up' noise louder also.

Digital transmission is free of noise and distortion as it can be 'cleaned', makign it preferable to analogue signals

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