95
Material Permitted
Paper Yes
Aluminium foil Yes
Cling fi lm Yes
Aluminium trays No
Freezer / microwave dishes Yes
Heat-resistant plastic Yes
Unglazed pottery No
Glazed pottery Yes
Metal cooking utensils No
Normal glass Yes
Pyrex and other ovenproof glass and ceramics Yes
Dishes with metallic decoration No
Metallic twist-ties No
Mercury thermometer No
Sealed pots No
Bottle with narrow neck No
Roasting bags Yes
How the microwave oven works
A microwave oven is a cooking appliance that uses microwaves to heat food. Microwaves
are electromagnetic waves, just like radio and television waves. A radio converts these
waves into sound, whereas a microwave oven converts them into heat.
The heat arises because the microwaves cause water and fat molecules, that are always
present in food, to move quickly. The molecules slide past each other quickly and friction
occurs. This friction causes heat (try rubbing your hands together quickly).
The microwave oven heats food very intensively, because the microwaves penetrate the
food directly. The waves do not just heat the outside of the food, but get right inside the
food. Compared to conventional methods of cooking, with small quantities, the cooking
time is much shorter.
4 Working
