Properties of Electromagnetic Waves

Electromagnetic waves travel in many planes (vertical as well as horizontal). Polarized sunglasses allow light to pass in only through a single plane, and block others. Therefore, as the amount of light coming in is reduced, glare is blocked to a great extent.

Electromagnetic waves are formed when there is a continuing oscillation of magnetic and electric fields. These waves form the electromagnetic radiation, which has both, electric as well as magnetic components. The presence and nature of these waves was first proposed by the scientist James Clerk Maxwell. It was confirmed when Heinrich Hertz demonstrated it.

As mentioned above, these waves are formed by oscillating electric and magnetic fields. The fields oscillate perpendicular to each other.

They are two-dimensional transverse waves, i.e., the transfer of energy is perpendicular to the oscillations.

Polarization of electromagnetic waves is possible.

Electromagnetic waves differ from mechanical waves in a way that the former do not require any medium of propagation. They can travel through matter as well as through vacuum.

These waves follow the laws of reflection, refraction, and diffraction.

These waves are not deflected by magnetic or electric fields.

Electromagnetic waves can show interference (superimposition of two waves over each other).

These waves travel through vacuum with a velocity of 3x10⁸ meters per second, i.e., the speed of light.

All types of electromagnetic waves travel at the speed of light in vacuum. However, their wavelengths vary.

The earth receives the maximum amount of electromagnetic energy from the sun. This energy reaches the earth through a vacuum.

Electromagnetic radiation consists of a stream of particles (photons) with energy, but, no mass. Therefore, the waves have momentum, but, no mass.

As the wavelength in the spectrum decreases, the amount of energy carried by the waves increase. This can be illustrated by the formula,

E= hc/λ

(where E is the energy,
h is Planck's constant,
c is speed of light in vacuum
λ is wavelength)

As these waves change their medium, their speed changes, however, frequency remains same. This is explained by the following equation:

v= fλ

(where v is the speed of the wave,
f is frequency,
λ is wavelength)

Waves in the electromagnetic spectrum can be divided into different types, depending on their wavelength (or frequency).

Different types of waves comprising the electromagnetic spectrum are infrared waves, ultraviolet rays, visible light rays, X-rays, gamma rays, microwaves, television, and radio waves.

One peculiar characteristic of electromagnetic radiation is that it displays both particle as well as wave properties at the same time.

High energy electromagnetic waves are X-rays, gamma rays, and ultraviolet rays. Low energy waves include radio waves, television waves, microwaves, infrared light, etc.

Electromagnetic radiation can exert pressure (known as the radiation pressure).

Bremsstrahlung is an interesting concept in the theory of electromagnetic radiation. Translated from German roughly as 'braking radiation/ray', it is a term used for electromagnetic radiation produced by deceleration of an electrically charged particle, when it collides with another particle.

Cherenkov radiation is another fascinating concept. It is the electromagnetic radiation that is emitted by a charged particle when it passes through a dielectric medium with a velocity greater than that of light (in that medium).

Cosmic microwave background radiation (CMBR) is the electromagnetic radiation spread over the entire universe. It was produced during the big bang.

The principle of electromagnetism is used for making electromagnets and Maglev (magnetic levitation) trains. Electromagnets are used in various fields. They are also used in nearly all electrical devices, MRI, etc.

Electromagnetic radiation can also cause danger and risk to human health. It is believed that certain types of cancer, skin diseases, digestive problems, etc., are caused due to this radiation. However, the effects and severity depends on the frequency of the radiation. Although it is considered a boon, its certain adverse effects cannot be ignored.