In the electromagnetic spectrum, radio waves have the longest wavelength, lowest frequency and lowest energy. They are mainly used for communication in devices such as televisions, Bluetooth-enabled devices and radios.
Oscillations in electrical circuits can produce radio waves.
Microwaves are used for satellite communication. Ovens also use microwaves; however, these microwaves need to be absorbed by water molecules within the food.
Infrared can be used for:
The region of the electromagnetic spectrum that the human eye can detect is known as the visible light spectrum.
Fibre optic cables transmit data using visible light that travels through glass fibres. The light travels from a source to a receiver, which can then be used by telephones or computers.
The wavelength of visible light is shorter than that of microwaves and radio waves, allowing it to carry more information. This makes it very useful in fibre optic cables.
Ultraviolet (UV) radiation is a type of radiation that is emitted by the sun and artificial sources (e.g. tanning beds). When exposed to UV through sunlight, your skin can tan or burn. However, if you are exposed to too much UV, it can be very dangerous.
Hospitals use both gamma (γ) rays and X-rays.
Gamma rays are useful for treating cancers, as the high dosage can kill cancer cells. However, sometimes, healthy cells are also killed. Gamma rays can also be used as medical tracers as they can pass throughout the body.
X-rays can be used to identify broken bones because they do not pass through bones as easily as they do through soft tissue.
High frequencies of electromagnetic waves can be harmful to people and can damage living tissue.
The absorption of ultraviolet radiation, X-rays, and γ rays is ionising, and it can damage body tissue. This is because they are all higher frequency electromagnetic waves, which carry more energy. This means that they can penetrate the body more easily and deeper than lower frequency waves.
The effect of the damage on the body tissue depends on the type of radiation and the size of the dose.
The Sievert (Sv) measures the radiation dose, indicating the risk of damage caused by the body’s exposure to radiation. As the absorption is usually less than 1 Sv, we tend to use milliSieverts (mSv).