Fri May 25, 2012 By: Milind Shrivastava

what is light and why it is denoted as energy?

Expert Reply
Fri May 25, 2012

Light is considered as an electromagnetic radiation. It consists of two components i.e., the electric component and the magnetic component which oscillate perpendicular to each other as well as to the direction of path of radiation. 

The electromagnetic radiations are produced by the vibrations of a charged particle. The properties of light can be explained by considering it as either wave or particle as follows. 

A photon is characterized by either a wavelength, denoted by ? or equivalently an energy, denoted by E. There is an inverse relationship between the energy of a photon (E) and the wavelength of the light (?) given by the equation:

where h is Planck's constant and c is the speed of light. The value of these and other commonly used constants is given in the constants page.

h = 6.626 × 10 -34 joule·s

c = 2.998 × 108 m/s

By multiplying to get a single expression, hc = 1.99 x 10-25 joules-m

The above inverse relationship means that light consisting of high energy photons (such as "blue" light) has a short wavelength. Light consisting of low energy photons (such as "red" light) has a long wavelength.

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