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FIFTH SEMESTER U.G. DEGREE EXAMINATION, NOVEMBER 2021
(CUCBCSS—UG)
Physics/Applied Physics
PHY 5B 07/APY 5B 08—QUANTUM MECHANICS
: Three Hours Maximum : 80 Marks
Section A

Answer all questions in a word or phrase.
Each question carries 1 mark.

Einstein’s photoelectric equation is

Write down the energy eigen value of particle in a one dimensional box.

Write down the uncertainty relation between energy and time.

Write down the selection rules for allowed transitions in a hydrogen atom.

Write down the one dimensional time dependent Schrodinger equation.

Write true or false:

Although they lack rest mass, photons behave as though they have gravitational mass.
A group of waves need have the same velocity as the waves themselves.

An electron can circle a nucleus only if its orbit contains an integral number of de Broglie
wavelengths.

For a harmonic oscillator the lowest energy will be E = 0.

The quantization of electron energy in the hydrogen atom is described by the principal quantum
number,

(10 x 1 = 10 marks)
Section B (Short Answer Type)

Answer all questions in two or three sentences.
Each question carries 2 marks.

Define group velocity.
State the postulates of Bohr atom model.

Write down the eigen value equation and define eigen value and eigen function.

Turn over

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