# Spectrum - Types of spectrum

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## spectrum

Spectrum basically plays an important role in physics and most of the concepts in physics are based on spectrum . when we come across the study of atomic nucleus , it becomes necessary for us to study spectrum . Spectrum is not only an alone concept , it has many types and each one is having a different role . so , in this article you will know its importance . Below I have discussed this concept means spectrum and its types . so lets read ;

what is spectrum ?

Spectrum is actually the ordered arrangement of radiations according to their wavelengths and frequencies.

spectrum

Origin of spectrum:

We know that each substance is actually made up of an atom and every atom is having a positively charged central core called as the nucleus of an atom.

 Spectrum

ðŸ‘‰ visit: Atomic model by Rutherford

We know that the nucleus of an atom consists of protons and neutrons. In the given figure we can see the electrons revolving around the nucleus. The number of electrons in the orbits is actually equal to the number of protons in the nucleus. Since the number of electrons in the inner orbits have less amount of energy as compared to the number of electrons in the outer orbits.

 Spectrum

### spectrum

When an external energy is supplied to the atom, the electron absorbs this energy and goes to the outer orbit . Now the atom is said to be in the excited state. The atom will return to its original state by emitting a certain amount of energy.

We know from Bohr's postulate;

hv = E"—E'

V = (E"—E')/h

By substituting the value of lambda, we can easily derive an expression for wavelength of emitted radiations.

spectrum

Types of Spectra :

There are two main types of spectra :-

Emission spectra

Absorption spectra

1) Emission spectra:

This type of spectra is observed when light emitted from the source is directly examined in a spectrometer. Emission spectra is further of Three types :-

a)  Continuous emission spectra :

A continuous emission spectra consists of unseperated wavelengths over a wide range. These types of spectra depend upon temperature. Spectra of sunlight, an incandescent bulb etc.are continuous emission spectra.

b)  Line emission spectra :

This type of spectra consists of few isolated bright coloured lines. This type of spectra is emitted by the atoms in the gaseous state. A sodium discharge lamp, a mercury vapour lamp etc emit line emission spectra.

c)  Band emission spectra :

This type of emission consists of number of bright coloured lights. Chemical compounds in vapour state emit this type of spectra. The spectra of iodine, oxygen molecules etc is  a band emission spectrum.

2) Absorption spectra:

This type of absorption spectrum is observed When light emitted from the source is first of all made to pass through an absorbing material and then examined in a spectroscope. The absorption spectrum is further of Three types :-

a)  continuous absorption spectra :

This type of spectrum is observed when we place red glass in the path of rays, it absorbs all the colours upto red .Thus we get absorption spectra continuous up-to red colour.

b)   Line absorption Spectra :

When we pass light from any kind of source through a gas or vapour ,then this gas absorbs certain wavelengths and hence dark lines are produced. These types of dark lines produced are called Line absorption spectrum.

c)  Band absorption spectra :

When white light is allowed to pass though the dilute solution of blood, then band absorption spectra is observed.

" Spectrum
Properties of Spectrum
Origin of spectrum
Types of spectrum
Emission spectrum
Absorption spectrum "