State Bohr's postulates in connection with structure of atom and derive the relation E n = − R c h n 2 where E n is energy in the n th level, R is Rydberg constant, c is speed of light and n is integer.

Let's consider an electron of mass m charge e revolve around the nucleus of positive charge Z e . The centripetal force is provided by the electrostatic force. m v 2 r = 1 4 πε 0 Z e 2 r 2 m v 2 = Z e 2 4 πε 0 r Divide both side by 2 K . E = m v 2 2 = Z e 2 8 πε 0 r Potential energy, P . E = - Z e 2 4 πε 0 r The energy of the electron in the nth orbit is given by, E = K . E + P . E E = - m Z 2 e 4 8 ε 0 2 h 2 n 2 This equation can be written in the terms of Rydberg constant. E = - Z 2 R h c n 2 Where , R = Rydberg contant R = m e 4 8 ε 0 2 c h 3 c = Speed of light

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12th ICSE

IMPORTANT

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Draw energy-level diagram for the hydrogen atom. Show transitions corresponding to lyman . In which regions of the spectrum do these series lie?

Important Questions on Atom, Origin of Spectra : Bohr's Theory of Hydrogen Atom

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12th ICSE

IMPORTANT

ISC Physics Class 12, Part-2>Chapter 13 - Atom, Origin of Spectra : Bohr's Theory of Hydrogen Atom>QUESTIONS>Q 9

Draw energy-level diagram for the hydrogen atom. Show transitions corresponding to Balmer series. In which regions of the spectrum do these series lie?

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12th ICSE

IMPORTANT

ISC Physics Class 12, Part-2>Chapter 13 - Atom, Origin of Spectra : Bohr's Theory of Hydrogen Atom>QUESTIONS>Q 10

Draw the energy level diagram of a hydrogen atom, showing first four energy levels corresponding to

n = 1, 2, 3

and

4

. Show transitions responsible for absorption spectrum of Lyman series.

HARD

12th ICSE

IMPORTANT

ISC Physics Class 12, Part-2>Chapter 13 - Atom, Origin of Spectra : Bohr's Theory of Hydrogen Atom>QUESTIONS>Q 10

Draw the energy level diagram of a hydrogen atom, showing first four energy levels corresponding to

n = 1, 2, 3

and

4

. Show transitions responsible for emission spectrum of Balmer series.

HARD

12th ICSE

IMPORTANT

ISC Physics Class 12, Part-2>Chapter 13 - Atom, Origin of Spectra : Bohr's Theory of Hydrogen Atom>QUESTIONS>Q 11

For Bohr's model of the hydrogen atom, the energy of the electron in its ground state is found to be

13.6 eV

. Draw an energy level diagram for the hydrogen atom and mark the values of energy (in

e V

) at

n = 1

n = \infty

MEDIUM

12th ICSE

IMPORTANT

ISC Physics Class 12, Part-2>Chapter 13 - Atom, Origin of Spectra : Bohr's Theory of Hydrogen Atom>QUESTIONS>Q 11

For Bohr's model of the hydrogen atom, the energy of the electron in its ground state is found to be

13.6 eV

. Obtain the maximum energy of a photon emitted by the hydrogen atom in

eV

HARD

12th ICSE

IMPORTANT

ISC Physics Class 12, Part-2>Chapter 13 - Atom, Origin of Spectra : Bohr's Theory of Hydrogen Atom>QUESTIONS>Q 1

State Bohr's postulates in connection with structure of atom and derive the relation

E_{n} = - \frac{R c h}{n^{2}}

where

E_{n}

is energy in the

n

th level,

R

is Rydberg constant,

c

is speed of light and

n

is integer.

HARD

12th ICSE

IMPORTANT

ISC Physics Class 12, Part-2>Chapter 13 - Atom, Origin of Spectra : Bohr's Theory of Hydrogen Atom>QUESTIONS>Q 2

Describe Rutherfored's

α

-scattering experiment and obtain an expression for closest approach.

HARD

12th ICSE

IMPORTANT

ISC Physics Class 12, Part-2>Chapter 13 - Atom, Origin of Spectra : Bohr's Theory of Hydrogen Atom>QUESTIONS>Q 3

Write Bohr's first postulate for angular momentum of an electron in any orbit and obtain the relation

r_{m} = \frac{n^{2} ε_{0} h^{2}}{π m Z e^{2}}

where symbols stands for usual meanings.

Draw energy-level diagram for the hydrogen atom. Show transitions corresponding to lyman . In which regions of the spectrum do these series lie?

Important Questions on Atom, Origin of Spectra : Bohr's Theory of Hydrogen Atom

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