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All the waves are transverse

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They all travel at the speed of light
They can all travel through a vacuum

The differences in the waves are due to their :

Penetrative powers

The electromagnetic spectrum

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Cooking with microwaves

A microwave oven uses radio waves to cook food very
The microwaves are produced by a ` magnetron ' and
guided by a metal stirrer which reflects the waves into
different parts of the oven
Microwaves are reflected by metal but absorbed by food
( about…

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The door must have a safety switch to turn of the
microwaves if you open the door ­ otherwise you could burn
your fingers!
Microwaves are also used for communicating with satellites


The water molecules in the outer layers vibrate more and
their kinetic energy increases
The energy…

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Infra ­ Red cookery

Energy from infra ­ red is absorbed by particles on the
surface of the food
This increases the kinetic energy of the particles
The energy is transferred to the rest of the food by

The differences between Infra ­ Red cooking and
microwave cooking

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Although microwaves are lower energy than infra ­ red and can
pass through glass and plastic, they can still cause burns, when
absorbed by body tissue

Frequency = 2450 MHz
Distance = 10 cm
Speed = 2.45 X 109

Microwaves in communications

Slightly lower energy waves are used in communications…

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The transmitters have to be fairly close together
otherwise diffraction ( spreading out of the wave ) and
( where signals cross over / meet ) can cause loss of signal

Dangers of microwaves in communications

Microwaves are used for communication as well as cooking
Recently there have been…

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