MICROWAVE OVEN
ABOUT MICROWAVE: THE SPECTRUM OF ELECTROMAGNETIC RADIATION CONTAINS A PART KNOWN AS AS MICROWAVES.THESE WAVES HAVE FREQUENCY AND ENERGY SMALLER THAN VISIBLE LIGHT AND WAVELENGTH LARGER THAN IT.
WHAT IS THE PRINCIPLE OF A MICROWAVE OVEN AND HOW DOES IT WORK? : OUR OBJECTIVE IS TO COOK FOOD OR WARM IT UP. ALL FOOD ITEMS SUCH AS FRUITS,VEGETABLES,MEAT,CEREALS ETC. CONTAIN WATER AS A CONSTITUENT. NOW ,WHAT DOES IT MEAN WHEN WE SAY THAT A CERTAIN OBJECT HAS BECOME WARMER?WHEN THE TEMPERATURE OF BODY RISES,THE ENERGY OF RANDOM MOTION OF ATOMS AND MOLECULES INCREASES AND THE MOLECULES TRAVELS OR VIBRATE OR ROTATE WITH THE HIGHER ENERGIES.THE FREQUENCY OF ROTATION OF WATER MOLECULES IS ABOUT 300 CRORE HERTZ WHICH IS 3 GIGAHERTZ(GHz).IF WATER RECEIVES MICROWAVES OF THIS FREQUENCY , ITS MOLECULES ABSORB THIS THIS RADIATION,WHICH IS EQUIVALENT TO HEATING UP WATER.THESE MOLECULES SHARE THIS ENERGY WITH NEIGHBOURING FOOD MOLECULES HEATING UP THE FOOD.
WHICH TYPE OF FOOD CONTAINER IS SAFE FOR THE MICROWAVE COOKING ?: ONE SHOULD USE PORCELAIN VESSELS AND NOT METAL CONTAINERS IN A MICROWAVE OVEN BECAUSE OF THE DANGER OF GETTING A SHOCK FROM ACCUMULATED ELECTRIC CHARGES. METAL MAY ALSO MELT FROM HEATING.THE PORCELAIN CONTAINER REMAIN UNAFFECTED AND COOL BECAUSE ITS LARGE MOLECULES VIBRATE AND ROTATE WITH MUCH SMALLER FREQUENCIES AND THUS CANNOT ABSORB MICROWAVES.HENCE THEY DO NOT GET HEATED UP.
THUS,BASIC PRINCIPLE OF A MICROWAVE OVEN IS TO GENERATE MICROWAVE RADIATION OF APPROPRIATE FREQUENCY IN THE WORKING SPACE OF OVEN WHERE WE KEEP FOOD.THIS WAY ENERGY IS NOT WASTED IN HEATING UP THE VESSEL.IN CONVENTIONAL HEATING METHOD,THE VESSEL ON THE BURNER GETS HEATED FIRST AND THEN THE FOOD INSIDE GETS HEATED BECAUSE OF TRANSFER OF ENERGY FROM THE VESSEL.IN THE MICROWAVE OVEN ON THE OTHER HAND ENERGY IS DIRECTLY DELIVERED TO WATER MOLECULES WHICH IS SHARED BY THE ENTIRE FOOD.
WHICH TYPE OF FOOD CONTAINER IS SAFE FOR THE MICROWAVE COOKING ?: ONE SHOULD USE PORCELAIN VESSELS AND NOT METAL CONTAINERS IN A MICROWAVE OVEN BECAUSE OF THE DANGER OF GETTING A SHOCK FROM ACCUMULATED ELECTRIC CHARGES. METAL MAY ALSO MELT FROM HEATING.THE PORCELAIN CONTAINER REMAIN UNAFFECTED AND COOL BECAUSE ITS LARGE MOLECULES VIBRATE AND ROTATE WITH MUCH SMALLER FREQUENCIES AND THUS CANNOT ABSORB MICROWAVES.HENCE THEY DO NOT GET HEATED UP.
THUS,BASIC PRINCIPLE OF A MICROWAVE OVEN IS TO GENERATE MICROWAVE RADIATION OF APPROPRIATE FREQUENCY IN THE WORKING SPACE OF OVEN WHERE WE KEEP FOOD.THIS WAY ENERGY IS NOT WASTED IN HEATING UP THE VESSEL.IN CONVENTIONAL HEATING METHOD,THE VESSEL ON THE BURNER GETS HEATED FIRST AND THEN THE FOOD INSIDE GETS HEATED BECAUSE OF TRANSFER OF ENERGY FROM THE VESSEL.IN THE MICROWAVE OVEN ON THE OTHER HAND ENERGY IS DIRECTLY DELIVERED TO WATER MOLECULES WHICH IS SHARED BY THE ENTIRE FOOD.
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