| Microwave output power |
| in Watts (based on |
| international (IEC 60705) |
| standard). |
| Letter representing the |
| oven heating category. |
Microwave Symbol. | |
OVEN | Less heating time required |
| |
OUTPUT | 600 700 800 900 1000 Watts |
POWER | More heating time required |
| |
OVEN | Less heating time required |
| |
OUTPUT | A B C D E |
CATEGORY | More heating time required |
| |
Microwaves are energy waves, similar to those used for TV and radio signals.
Electrical energy is converted into microwave energy, which is directed into the oven cavity via a waveguide. To prevent food and grease entering the wave guide it is protected by the waveguide cover.
Microwaves cannot pass through metal, because of this the oven cavity is made of metal and there is a fine metal mesh on the door. During cooking the microwaves bounce off the sides of the oven cavity at random.
The heating category (a letter A to E) developed by MAFF (Ministry of Agriculture, Fisheries and Food) with microwave oven and food manufacturers indicates the ability of the oven to heat small quantities of food (up to 500g [ I lb 2oz]). It does not represent the general performance of the oven.
Food packs carry cooking instructions for heating categories A to E. Follow instructions for the letter corresponding to the oven's heating category. The higher the output power and heating category of the oven the less heating time is required as shown opposite.
Microwaves will pass through certain materials, such as glass and plastic, to heat the food. (See 'Suitable Cookware' on page
Water, sugar and fat in food absorb microwaves which cause them to vibrate. This creates heat by friction, in the same way your hands get warm when you rub them together.
The outer areas of the food are heated by the micro- wave energy, then the heat moves to the centre by conduction, as it does in conventional cooking. It is important to turn, rearrange or stir food to ensure even heating.
Once cooking is complete, the oven automatically stops producing microwaves.
Standing time is necessary after cooking, as it enables the heat to disperse equally throughout the food.
