12
MICROWAVING PRINCIPLES
Microwave energy has been used in this country to cook and reheat food since early experiments with RADAR in
World War ll. Microwaves are present in the atmosphere all the time, both naturally and manmade sources.
Manmade sources include radar, radio, television, telecommunication links and car phones.
Microwave oven is a Group 2 ISM equipment in which radio frequency energy is intentionally generated and used in
the form of electromagnetic radiation for the treatment of material. This oven is a Class B equipment suitable for use in
domestic establishments and in establishments directly connected to a low voltage power supply network which
supplies buildings used for domestic purposes.
CONVERSION CHARTS
WEIGHT MEASURES
15 g
1
/2 oz.
25 g 1 oz.
50 g 2 oz.
100 g 4 oz.
175 g 6 oz.
225 g 8 oz.
450 g 1 lb.
HOW MICROWAVES COOK FOOD
VOLUME MEASURES
30 ml 1 fl.oz.
100 ml 3 fl.oz.
150 ml 5 fl.oz. (
1
/
4 pt)
300 ml 10 fl.oz. (
1
/
2 pt)
600 ml 20 fl.oz. (1pt)
SPOON MEASURES
1.25 ml
1
/4 tsp
2.5 ml
1
/
2 tsp
5 ml 1 tsp
15 ml 1 tbsp
FLUID MEASUREMENTS
1 Cup = 8 fl.oz. = 240 ml
1 Pint = 16 fl.oz. (UK 20 fl.oz.) = 480 ml (UK 560 ml)
1 Quart = 32 fl.oz. (UK 40 fl.oz.) = 960 ml (UK 1120 ml)
1 Gallon = 128 fl.oz. (UK 160 fl.oz.) = 3840 ml (UK 4500 ml)
Then they pass through
the cooking containers to
be absorbed by the water
molecules in the food, all
foods contain water to a
more or lesser extent.
The microwaves cause the water molecules to
vibrate which causes FRICTION, i.e. HEAT. This
heat then cooks the food. Microwaves are also
attracted to fat and sugar particles, and foods high
in these will cook more quickly. Microwaves can
only penetrate to a depth of
4-5cm and as heat spreads through the food by
conduction, just as in a traditional oven, the food
cooks from the outside inwards.
In a microwave oven,
electricity is converted
into microwave by the
MAGNETRON.
The microwaves
bounce off the metal
walls and the metal
door screen.
Oven Cavity
Magnetron
Waveguide
Turntable
REFLECTION
TRANSMISSION
ABSORPTION
Microwave Water Molecule Absorption Vibration
