Pages in this set

Page 1

Preview of page 1
Waves

All the waves are transverse

Page 2

Preview of page 2
They all travel at the speed of light
They can all travel through a vacuum

The differences in the waves are due to their :

Wavelength
Frequencies
Penetrative powers




The electromagnetic spectrum

Page 3

Preview of page 3
Cooking with microwaves

A microwave oven uses radio waves to cook food very
quickly
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…

Page 4

Preview of page 4
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




Microwave
cookery

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

Page 5

Preview of page 5
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
conduction




The differences between Infra ­ Red cooking and
microwave cooking

Page 6

Preview of page 6
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…

Page 7

Preview of page 7
The transmitters have to be fairly close together
otherwise diffraction ( spreading out of the wave ) and
interference
( 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…

Page 8

Preview of page 8

Comments

No comments have yet been made

Similar Physics resources:

See all Physics resources »