# Nootan Solutions Atom, Origin of Spectra : ISC Physics Class-12 Ch-26

Nootan Solutions Atom, Origin of Spectra ISC Physics Class-12 Ch-26 Vol-2 Nageen Prakashan.  Step by step Solutions of Numericals of latest edition of Kumar and Mittal ISC Physics Part-2 Class-11 Nageen Prakashan Questions. Visit official Website CISCE for detail information about ISC Board Class-12 Physics.

## Nootan Solutions Atom, Origin of Spectra ISC Physics Class-12 Ch-26

 Class: 12 Subject: Physics Part-2 Chapter: 26 Atom, Origin of Spectra : Bohr’s Theory of Hydrogen Atom
 Board ISC Writer / Publications Nootan / Nageen Prakashan / Kumar and Mittal Topics Solved Numericals of page 959, 960

### Nootan Solutions Atom, Origin of Spectra ISC Physics Class-12 Ch-26 Vol-2 Kumar and Mittal

#### Bohr’s Equation :-

Bohr Model of the hydrogen atom first proposed the planetary model, but later an assumption concerning the electrons was made. The assumption was the quantization of the structure of atoms. Bohr’s proposed that electrons orbited the nucleus in specific orbits or shells with a fixed radius. Only those shells with a radius provided by the equation below were allowed, and it was impossible for electrons to exist between these shells.

Mathematically, the allowed value of the atomic radius is given by the equation:

r(n) = × r(1)

Where,

• n is a positive integer
• r(1) is the smallest allowed radius for the hydrogen atom also known as the Bohr’s radius

#### Limits of the Bohr Model :-

• It could not explain why some spectral lines split into multiple lines in the presence of a magnetic field.
• The Heisenberg’s uncertainty principle contradicts Bohr’s idea of electrons existing in specific orbits with a known radius and velocity.
• Bohr’s model doesn’t work well for complex atoms.
• It couldn’t explain why some spectral lines are more intense than others.

#### Atomic Spectra :

Atomic spectra are defined as
The spectrum of the electromagnetic radiation emitted or absorbed by an electron during transitions between different energy level within an atom.

When an electron gets excited from one energy level to another, it either emits or absorbs light of a specific wavelength. The collection of all these specific wavelengths of the atom in a given set of conditions like pressure, temperature, etc is the atomic spectra of atoms. There are three types of atomic spectra and they are emission spectra, absorption spectra, and continuous spectra.

Nootan Solutions Atom, Origin of Spectra ISC Physics Class-12 Ch-26

### (Page 959, 960)

Question 1 :

The energy of an ………………… nuclease of silver ?

Question 2:

α particle …………………. energy then ?

Question 3:

…………………

…………………

………………….

Question 22:

The energy of hydrogen …………………….. in this process ?

Question 23:

………………….

………………..

………………….

Question 38:

The wavelength of a ……………… wave number.

—: End of Nootan Solutions Atom, Origin of Spectra :–

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