Electromagnetic Waves

Definition and Properties

Electromagnetic waves are waves that can travel through the vacuum of outer space. They do not require a medium like air or water to propagate.
They are formed by oscillating electric and magnetic fields at right angles to each other, and both are perpendicular to the direction of wave propagation.
Electromagnetic waves are transverse waves, which means the disturbance is perpendicular to the direction of the wave.

They move at the speed of light ((3.0 \times 10^8) m/s), in a vacuum.
They can be reflected, refracted, and diffracted and can interfere with each other.
The frequency of an electromagnetic wave determines its position in the electromagnetic spectrum and its properties.

The electromagnetic spectrum is a continuous range of electromagnetic waves arranged from low frequency (long wavelength) to high frequency (short wavelength).
It includes (from low frequency to high frequency): radio waves, microwaves, infra-red waves, visible light, ultraviolet light, X-rays, and gamma rays.
These waves differ in their wavelengths and frequencies, but they all travel at the same speed in a vacuum.

Radio waves are used for broadcasting radio and television programmes.
Microwaves are utilized in radar, telecommunications and for heating food in microwave ovens.
Infra-red waves are used for thermal imaging, remote controls and fibre-optic communications.
Visible light enables humans and many animals to see.
Ultraviolet light has various medical applications, but too much can be harmful and can cause skin cancer.
X-rays are used in medical imaging and treatment.
Gamma rays are used in cancer treatments, sterilizing medical equipment, and in radioactive tracers.

Prolonged exposure to high-frequency electromagnetic waves (UV, X-rays, gamma rays) can be very harmful and can cause skin cancer, eye damage, and other diseases. They affect living cells and can break chemical bonds.
Lower frequency waves (microwaves, radio waves), although not as harmful, can still be dangerous if exposure is constant and/or in high doses. For instance, microwaves can heat body tissue and cause internal burns.