Panasonic NN-ST667W, NN-ST677M manual Microwaves and How They Work, Cookware and Utensils Guide

Microwaves and￿ How They Work

Microwaves are a form of high frequency radio waves similar to those used by a radio, including AM, FM and CB. They are similar to a television where the radio waves are converted to a picture on the screen. However, microwaves are much shorter than radio waves; approximately twelve centimetres wave length. Electricity is converted into microwave energy by the magnetron tube (which is the heart of the microwave oven).

From the magnetron tube, microwave energy is transmitted to the oven cavity through a small plastic covered piece. The microwaves are converted to heat in the food. The microwaves enter from the outside of the food and travel through the food losing half of their power every two to three centimetres. Continued cooking to the centre occurs by conduction.

Although pacemakers used to be affected by microwaves (as well as by other radio waves), they are now shielded and are not bothered by these interferences. This allows people with pacemakers to sit calmly by their radio or television and cook with microwave ovens.

When microwaves come in contact with a substance, any one or combination of three things may occur. They can be:

1.REFLECTED

2.TRANSMITTED

3.ABSORBED

Reflection:

Metal substances REFLECT microwave energy and because there is no absorption, there is no heating. This is why the oven interior is either stainless steel or epoxy-coated steel. This ensures that the microwaves are kept inside the cavity and evenly distributed throughout the food with the help of the turntable.

Transmission:

Such substances as paper, glass and plastic TRANSMIT microwave energy and do not become hot except from food. Because these substances do not reflect or absorb microwave energy, they are ideal materials for microwave cooking containers.

Absorption:

Food contains moisture and will ABSORB microwave energy, which causes the moisture molecules within the food to vibrate at an incredible rate (2,450,000,000 times per second). Friction, created by the vibration, produces heat energy which is conducted throughout the food.

Cookware and Utensils Guide

It is important to use the correct container when cooking in a microwave oven. The following will help you make the right selection.

How to Test a Container for Safe Microwave Oven Use

TO TEST A CONTAINER FOR SAFE MICROWAVE OVEN USE: Fill a 1-cup glass measure with cool water and place it in the microwave oven alongside the empty container to be tested; heat one (1) minute at P10. If the container is microwave oven- safe (transparent to microwave energy), the container should remain comfortably cool, the water in glass measure should be hot. If the container is hot, it has absorbed some microwave energy and should NOT be used. This test cannot be used for plastic containers.

Paper Products and Freezer Wrap

Waxed paper, paper plates, cups and napkins should not be used for heating or cooking food. Freezer wrap should not be used as it is not heat resistant and may melt. Paper towel, greaseproof paper and bake paper may be safely used for short periods of time for covering or lining.

Glass, Ceramic and China

Heat-Resistant glass cookware is invaluable in microwave cooking. Many of these items are readily available in most homes: glass jugs, mixing bowls, loaf dishes, covered casseroles, oblong baking dishes, pie plates and round or square cake dishes. Examples of this type of cookware are Pyrex® and Corningware®.

Dinnerware can be used for microwave heating. Many brands of dinnerware are microwave safe. Check the care information for reference to microwave use for dinnerware and serving pieces. If dinnerware is marked ovenproof, it frequently is safe to use in the microwave oven. However, to be sure, check by conducting microwave dish test previously mentioned.

Several types of glassware and dinnerware are not recommended for use in the microwave oven. Do not use dishes with metallic trim or containers with metal parts. Do not use cups or mugs with glued on handles, as they may fall off with continued heating. Do not use delicate glassware. Although the glassware may be transparent to microwave energy the heat from the food may cause the glassware to crack.

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