19
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.
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
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.
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
