The phenomenon called electromagnetic induction was first noticed and investigated by Faraday, and the law of induction is its quantitative expression. Faraday discovered that whenever the magnetic field about an electromagnet was made to grow and collapse by closing and opening the electric circuit of which it was a part, an electric current.

electromagnetic radiation, in classical physics, the flow of energy at the universal speed of light through free space or through a material medium in the form of the electric and magnetic fields that make up electromagnetic waves such as radio waves, visible light, and gamma rays.

Ultraviolet astronomy is also best done from space. Electromagnetic radiation with wavelengths between roughly 400 and 700 nm is called visible light because these are the waves that human vision can perceive. This is also the band of the electromagnetic spectrum that most readily reaches Earth’s surface.

Electromagnetic waves are categorized according to their frequency f or, equivalently, according to their wavelength λ = c/f. Visible light has a wavelength range from ~400 nm to ~700 nm. Violet light has a wavelength of ~400 nm, and a frequency of ~7.5*10 14 Hz. Red light has a wavelength of ~700 nm, and a frequency of ~4.3*10 14 Hz.

Electromagnetic radiation is self-sustaining energy with electric and magnetic field components. Electromagnetic radiation is commonly referred to as "light", EM, EMR, or electromagnetic waves. The waves propagate through a vacuum at the speed of light.

Electromagnetic radiation with wavelengths between roughly 400 and 700 nm is called visible light because these are the waves that human vision can perceive. This is also the band of the electromagnetic spectrum that most readily reaches Earth’s surface.

Electroweak theory unifies the theory of quantum electrodynamics (QED), the modern equivalent of classical electromagnetism, and the theory of weak nuclear interactions. The Standard Model combines the theory of relativity and quantum mechanics. In the Standard Model, particle interactions occur through the exchange of bosons, the “force carriers.”

In the visible range of light these are called photons and in the invisible range, i.e Infrared, UV and others the energy are called quanta. When a electron gains a certain amount of energy then it jumps to a higher energy orbit unless it has absorbed so much energy that its ejected, it again comes back to its original orbit after losing the.

Mechanical waves, such as sound, require a medium through which to travel, while electromagnetic waves ( see electromagnetic radiation) do not require a medium and can be propagated through a vacuum. Propagation of a wave through a medium depends on the medium’s properties. See also seismic wave. Types and features of waves