Microwave oven

A microwave oven, or simply microwave, is an electric oven that heats and cooks food by exposing it to electromagnetic radiation in the microwave frequency range. This induces polar molecules in the food to rotate and produce thermal energy (heat) in a process known as dielectric heating. Microwave ovens heat food quickly and efficiently; the heating effect is fairly uniform in the outer 25–38 mm (1–1.5 inches) of a homogeneous, high-water-content food item.

The development of the cavity magnetron in the United Kingdom made possible the production of electromagnetic waves of a small enough wavelength (microwaves) to efficiently heat up water molecules. American electrical engineer Percy Spencer is generally credited with developing and patenting the world's first commercial microwave oven, the Raytheon "Radarange", which was first sold in 1947. He based it on British radar technology which had been developed before and during World War II.

Raytheon later licensed its patents for a home-use microwave oven that was first sold by Tappan in 1956, but it was still too large and expensive for general home use. Sharp Corporation introduced the first microwave oven with a turntable between 1964 and 1966, this feature created more even heating than the earlier microwave stirrer feature. The countertop microwave oven was introduced in 1967 by the Amana Corporation, which was, at the time, owned by Raytheon. After microwave ovens became affordable for residential use in the late 1970s, their use spread into residential kitchens around the world, and prices fell rapidly during the 1980s. In addition to cooking food, microwave ovens are used for heating in many industrial processes.