Microwaves are a type of electromagnetic radiation, similar to radio waves, ultraviolet radiation, X-rays, and gamma-rays. They are defined as electromagnetic radiations with a frequency ranging between 300 MHz to 300 GHz, and a wavelength ranging from 1 mm to around 30 cm. Microwaves are used in a variety of applications, including communications, radar, and cooking. Some key properties of microwaves include:

• Absorption by water: Microwaves of certain frequencies are absorbed by water, which is why they are useful in cooking. Water in the food absorbs microwaves, which causes the water to heat up and cook the food.

• Reflection by metal: Microwaves are reflected by metal surfaces, which is why metal containers are not used in microwave ovens.

• Passage through glass and plastic: Microwaves can pass through glass and plastic, which is why these materials are used in microwave-safe containers.

Microwaves are used in point-to-point communication systems to convey all types of information, including voice, data, and video in both analog and digital formats. They are also used for supervisory control and data acquisition (SCADA) for remote machinery, switches, valves, and signals. Another important application of microwaves is radar, which is used to detect the presence and locations of distant objects like ships and aircraft. One of the most common uses of microwaves is to heat food quickly, which is made possible by the discovery that microwaves can be used to transmit thermal energy.

Microwaves are non-ionizing radiation, which means that they do not have the same risks as X-rays or other types of ionizing radiation. They are generally safe when used correctly, and the main effect of absorption of microwaves is to heat materials.