1.7.7

Infrared, Microwave & Radio Waves

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Infrared Radiation

Infrared (or infra-red) radiation is one type of wave on the electromagnetic spectrum.

Uses

Uses

  • Infra-red radiation is used in TV controls.
  • Infra-red can also be used for security purposes, such as in intruder alarms by detecting body heat.
Risks

Risks

  • Infra-red radiation can cause serious skin burns if emitted from high-intensity sources.
Explanation

Explanation

  • The frequency is high enough to excite particles in food. This increases their temperature.
  • Infra-red cameras can detect a range of frequencies. These frequencies can be shown in different colours to depict images.

Microwaves

Microwaves are the 6th type of wave in the electromagnetic spectrum.

Uses

Uses

  • Microwaves are used for the purpose of satellite communications (transmitting signals between stations on Earth and satellites).
  • Microwaves are also used to transmit signal from a nearby phone mast (transmitter) to a mobile phone.
  • Microwaves are absorbed by water, heating up the water in the process. This makes microwaves useful for cooking food because food contains lots of water.
Risks

Risks

  • Because humans are largely made up of water, exposure to microwaves could have a harmful effect.
Safety

Safety

  • We should always reduce any exposure to microwaves.
  • As with X-rays, always have some sort of shielding between the source of microwaves and living tissue.
  • An example of this is the protective shielding on microwave ovens.
Explanation

Explanation

  • Microwaves have a high enough frequency to penetrate the Earth’s atmosphere and to reach satellites.
  • Microwaves travel in straight lines through the atmosphere. This makes them good for transmitting (sending) signals.

Radio Waves

Radio waves are used for radio and TV communications.

Uses

Uses

  • Radio waves are used for radio and TV communications.
Risks

Risks

  • At high intensities, radio waves can cause internal heating of living tissue with potentially harmful effects.
Explanation

Explanation

  • Because radio waves have long wavelengths, they can be transmitted (sent) around the Earth’s surface and around buildings without interference.
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1

Principles of Science I

1.1

Structure & Bonding

1.2

Properties of Substances

1.3

Cell Structure & Function

1.4

Cell Specialisation

1.5

Tissue Structure & Function

1.6

Working with Waves

1.7

Waves in Communication

2

Practical Scientific Procedures and Techniques

3

Science Investigation Skills

4

Principles of Science II

4.1

Extracting Elements

4.2

Relating Properties to use of Substances

4.3

Organic Chemistry

4.4

Energy Changes in Industry

4.5

The Circulatory System

4.6

Ventilation & Gas Exchange

4.7

Urinary System

4.8

Cell Transport

4.9

Thermal Physics

4.10

Materials

4.11

Fluids

5

Contemporary Issues in Science

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