Electromagnetic radiation
Introduction
Electromagnetic radiation (EMR) is a form of energy that is all around us and takes many forms, such as X-rays, radio waves, heat, and light. It is a type of energy that travels and spreads out as it goes, visible light that comes from a lamp in your house or radio waves that come from a radio station are two types of electromagnetic radiation. Other examples of electromagnetic radiation are microwaves, infrared radiation, ultraviolet light, gamma rays, and X-rays.
Fundamentals of Electromagnetic Radiation
Electromagnetic radiation is characterized by a broad range of wavelengths and frequencies, each associated with a specific intensity (or amplitude). This broad range of wavelengths is known as the electromagnetic spectrum. The spectrum is generally divided into seven regions in order of decreasing wavelength and increasing energy and frequency. The common designations are radio waves, microwaves, infrared (IR), visible light, ultraviolet (UV), X-rays and gamma rays.
Properties of Electromagnetic Radiation
Electromagnetic radiation has both electric and magnetic field components, which oscillate in phase perpendicular to each other and perpendicular to the direction of energy propagation. Electromagnetic radiation is classified into types according to the frequency of the wave: these types include, in order of increasing frequency, radio waves, microwaves, terahertz radiation, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.
Interaction with Matter
Electromagnetic radiation interacts with matter in various ways across the spectrum. These interactions can be as simple as a molecule absorbing a photon and re-emitting it with a slightly longer wavelength, to more complex interactions such as Compton scattering. The way in which EM radiation interacts with matter can tell us much about the nature of the matter itself.
Generation of Electromagnetic Radiation
Electromagnetic radiation is produced by the motion of electrically charged particles. These particles move in all kinds of different ways and give off energy as electromagnetic radiation. For example, a changing electric field generates a changing magnetic field, and vice versa. This interplay between electricity and magnetism is where the term "electromagnetic" comes from.
Applications of Electromagnetic Radiation
Electromagnetic radiation has many practical applications in our daily lives, including certain types of communication, medical imaging, and the generation of electrical power. The specific application depends on the wavelength and frequency of the radiation.
Health Effects of Electromagnetic Radiation
While electromagnetic radiation from sources such as the Sun is vital for life, excessive exposure can cause tissue damage. Exposure risk depends on the wavelength and intensity of the radiation, as well as the duration and nature of exposure.