Most of us are familiar with microwave oven. We shortly call it microoven. It is an useful machine for a comfortable life. It is an essential kitchen appliances. It is used to heat food. There is an interesting thing in a microwave oven.When we give food in a microwave oven within a plate, only the food become hot but the plate do not get hot. But why do the plate not become hot? Today I am going to tell you about the formula of a microwave oven.
Percy Spencer invented the first microwave oven after World War II from radar technology developed during the war. Named the “Radarange”, it was first sold in 1947.Raytheon later licensed its patents for a home-use microwave oven that was first introduced by Tappan in 1955, but these units were still too large and expensive for general home use. The countertop microwave oven was first introduced in 1967 by the Amana Corporation, which was acquired in 1965 by Raytheon.
The heart of every microwave oven is the high voltage system . Its purpose is to generate microwave energy. The high-voltage components accomplish this by stepping up AC line voltage to high voltage, which is then changed to an even higher DC voltage. This DC power is then generated to microwaves that creates thermal energy cooks the food. Actually, the main theme of a microwave oven is hidden in its name. Micro + Wave + Oven. In a microwave oven microwaves is used to heat food. Generally, waves of 2500 MHz or 2.5GHz is used in microwave oven. There are many types of microwave, but electromagnetic wave is used in this machine. Microwave oven heats food by bombarding it with electromagnetic radiation in the microwave spectrum causing polarized molecules in the food to rotate and build up thermal energy in a process known as dielectric heating. It heat foods quickly because excitation is fairly uniform in the outer 25–38 mm of a dense food item containing lot of water.
Now, the question is why the plate don’t become hot. Because the wave which is used in the microwave oven can easily pass through siramics, glass & most of plastic type materials. So, the plate do not become hot. On the other hand foods absorb the wave and become hot.
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