When studying the electromagnetic spectrum, one encounters Electromagnetic Waves. These are waves where the electric and magnetic field vectors change sinusoidally and are at right angles to each other, and the direction of wave propagation.
This topic is part of the General Science section of the UPSC Syllabus.
In essence, Electromagnetic waves are synchronized oscillations of electric and magnetic fields. These waves travel at the speed of light when in a vacuum, a speed denoted as c. The waves form a transverse wave when the oscillations of the two fields are perpendicular to each other and the direction of energy and wave propagation, provided the medium it passes through is homogeneous.
An electromagnetic wave's position within the spectrum can be characterized by its frequency of oscillation or its wavelength. Different frequencies of Electromagnetic waves are named differently as they have distinct sources and effects on matter. In order of increasing frequency and decreasing wavelength, these are radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays.
Electromagnetic waves are created by particles that are accelerating and electrically charged. This charge allows them to interact with other charged particles. EM waves carry energy, momentum, and angular momentum away from their source particle and can impart those quantities to matter with which they interact. Electromagnetic radiation is associated with those EM waves that can propagate themselves (“radiate”) without the continuing influence of the moving charges that produced them because they have achieved sufficient distance from those charges.
The effects of Electromagnetic Waves (EMW) on chemical compounds and biological organisms depend on the power and its frequency. EMW of visible or lower frequencies (i.e., visible light, infrared, microwaves, and radio waves) is referred to as non-ionizing radiation because its photons do not individually have enough energy to ionize atoms or molecules or break chemical bonds. The effects of these radiations on chemical systems and living tissue are primarily caused by heating effects from the combined energy transfer of many photons.
The World Health Organization has classified radiofrequency radiation from electromagnetic waves as Group 2B – possibly carcinogenic. This group contains possible carcinogens such as lead, DDT, and styrene.
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