How Your Microwave Oven Works - Westinghouse WST3504 User Instructions

Materials to Avoid in a Microwave Oven
Cooking
Accessories
(not included with Microwave)
Aluminum pan or tray
Food carton with
metal handle
Metal or metal-trimmed
utensils
Metal twist ties
Plastic foam
Wood
The microwave oven has an electronic tube called a magnetron that produces microwaves, very short radio
waves. The microwaves then pass through a wave-guide and into the oven cavity. The microwaves penetrate the
food and cause water molecules within the food to vibrate extremely rapidly. This vibration causes considerable
friction or heat between the water molecules resulting in a rapid rise in temperature. This type of heating is very
efficient and the cooking time is therefore shorter than in a conventional oven. The rate of heating depends on
the moisture content, shape, volume and amount of food present. Metallic materials totally reflect microwaves.
Non-metallic materials such as glass, paper and plastics are partially transparent to microwaves. Microwaves do
not directly heat the oven walls and most cooking utensils because they do not absorb microwave energy.
However, they frequently get very warm through being in direct contact with hot food.
Remarks
May cause arcing. Transfer food into microwave-safe dish.
May cause arcing. Transfer food into microwave-safe dish.
Metal shields the food from microwave energy and may cause arcing.
May cause arcing and could cause a fire in the oven.
Plastic foam may melt or contaminate the liquid inside when exposed to high temperature.
Wood will dry out and may split. Avoid using wooden containers or utensils in the oven.

How Your Microwave Oven Works

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