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Why Sparks Occur When Cooking Vegetables in a Microwave

When cooking certain vegetables in a microwave, sparks may occur and, on closer examination, the vegetables may display small burns.

Dense vegetables such as green beans, carrots and green peppers have a higher amount of minerals in them than other food items. These minerals include iron, magnesium and selenium.

Arcing effects in microwaves

The minerals act like tiny pieces of metal and create arcing effects in a microwave. The sparks result as the microwaves reflect or bounce off the metal. The arcing does not harm the food but it does prevent it from heating thoroughly.

Extensive arcing can damage the oven's magnetron tube.

Additional information