14
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
