The microwave oven was accidentally invented by Percy Spencer when working with a magnetron that generated microwave radiation, which caused his candy bar to melt. The oscillating electric field component of the electromagnetic wave generates friction and heat in water molecules, which cooks food so uniformly and without external heat. A metal cavity reflects electromagnetic waves back and forth, creating resonance that intensifies the wave energy and heats the food. The wavelength of the standing waves in the structure determines the oven’s dimensions, which creates some hot and cold spots, but a rotating plate helps to cook food evenly. Microwaves cook food faster and penetrate it, while conventional methods cook from the outside in for crispy surfaces and baking.
- 00:00:00 In this section, we learn about the accidental invention of the microwave oven by scientist Percy Spencer while working with a device called a magnetron. Microwave radiation was generated by the magnetron which was later observed to cause a candy bar in Spencer’s pocket to melt. The reason microwaves can cook foods so uniformly and without external heat is due to the oscillating electric field component of the electromagnetic wave which is responsible for cooking food. Electromagnetic waves generate friction and heat in the water molecules of food. The wave energy is trapped and reflected using metal to achieve resonance cavity, which increases the intensity of electromagnetic waves that cause the food to heat up.
- 00:05:00 In this section, we learn that the dimensions of a microwave oven are determined by the wavelength of the standing waves produced in the closed structure. The standing waves have hot and cold spots due to high energy intensity and zero intensity points, respectively. This creates uneven heating, but a rotating plate now helps to cook food evenly. Microwaves are superior to conventional heating methods as they penetrate the food and cook it faster while slowly cooking the surface. The convection method, on the other hand, cooks food from the outside in, which is useful for crisp surfaces and baking.