Which of the following is used in the oven?
(1) X-rays
(2) UV rays
(3) Microwaves
(4) Radiowaves
Answer: (3) An oven that uses micro radiation waves as a source of heat to cook food as opposed to a fire source. Conceptualized in 1946, Dr Perry Spencer allegedly discovered the healing properties of microwaves while studying the magnetron. A microwave oven, often colloquially shortened to microwave, is a kitchen appliance that heats food by dielectric heating accomplished with radiation used to heat polarized molecules in food. Microwave ovens heat foods quickly and efficiently because excitation is fairly uniform in the outer 25–38 mm of a dense (high water content) food item; food is more evenly heated throughout (except in thick, dense objects) than generally occurs in other cooking techniques. A microwave oven works by passing non-ionizing microwave radiation, usually at a frequency of 2.45 gigahertz (GHz)—a wavelength of 122 millimetres (4.80 in)—through the food. Microwave radiation is between common radio and infrared frequencies.
