20
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.
In a microwave oven,
electricity is
converted into
microwave by the
MAGNETRON.
REFLECTION
The microwaves
bounce off the
metal walls and the
metal door screen.
TRANSMISSION
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.
ABSORPTION
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 1
1
/2 - 2 inches(4-
5cm) and as heat spreads through the food by
conduction, just as in a traditional oven, the food
cooks from the outside inwards.
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
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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)
CONVERSION CHARTS
