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MPH602S - MODERN PHYSICS - 1ST OPP - NOVEMBER 2024 |
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nAm IBIA UnlVERSITY
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ChemistryandPhysics
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QUALIFICATION: BACHELOR OF SCIENCE
QUALIFICATION CODE: 07BOSC
COURSE: MODERN PHYSICS
DATE: NOVEMBER 2024
DURATION: 3 HOURS
LEVEL:6
COURSECODE: MPH602S
SESSION: 1
MARKS: 100
FIRST OPPORTUNITY: EXAMINATION QUESTION PAPER
EXAMINER:
MODERATOR:
INSTRUCTIONS:
PROF SYLVANUS ONJEFU
PROF DIPTI SAHU
1. Answer all questions on the separate answer sheet.
2. Please write neatly and legibly.
3. Do not use the left-side margin of the exam paper. This must be allowed for the
examiner.
4. No books, notes and other additional aids are allowed.
5. Mark all answers clearly with their respective question numbers.
PERMISSIBLE MATERIALS
1. Non-Programmable Calculator
ATTACHMENTS
1. None
This paper consists of 4 pages including the front page
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Physical Constant
Electron mass
Proton mass
Planck constant
Speed of light
leV
me= 9.11 x 10- 31kg
mp= 1.6736 x 10- 27 kg
h = 6.625 X 10 -34J
c = 3 xl0 8 m/s
1.6 X 10 -l 9
QUESTION 1
[22 MARKS]
1.1 A radioactive element has 3.0 x 10 6 atoms and the decay constant= 5.4 x 10- 7 s-1•
Calculate (a) its half-life (b) the rate of disintegration (c) average life.
(6)
1.2 When a nucleus of 2~: Ra emits
(i) alpha particle (ii) beta particle (iii) gamma ray (iv) neutron. What is the resulting
nucleus in each case?
(8)
1.3 Assuming that photon obeys plank's energy rule. At what frequency will photons
have the following energies (a) 0.010 eV and (b) 3.0 eV. In each case, determine
the wavelength in micrometers.
(8)
QUESTION2
2.1 Explain how band spectra is obtained in an atom.
[16 MARKS]
(2)
2.2 When light of wavelength 450 nm is incident on a ce11ain metal, electrons are
emitted with kinetic energies up to 2.0 eV.
2.2. I What is the work function of the metals?
(4)
2.2.2 What is the minimum frequency needed to emit any photoelectrons?
(4)
2.4 An electron falls from rest through a potential difference of 100 V. What
is its de Broglie wavelength?
(6)
The KE gained 1/2mv 2 is equal to the electrical PE lost Vq. Therefore,
Modern Physics (MPH602S)
P 1Opportunity November 2024
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QUESTION3
[20 MARKS]
3.1 Determine the de Broglie wavelength for a particle moving with a speed
2.0 x 10 6 mis if the particle is;
3.1.1 a 0.20 kg.
(5)
3.1.2 an electron.
(5)
3.1.3 a proton.
(5)
3.2 Explain a blackbody and a blackbody radiation.
(5)
QUESTION 4
[20 MARKS]
4.1 Using Compton Effect: X-rays of wavelength 0.140 nm are scattered from a thin
slice of carbon. What will be the wavelengths of X-rays scattered at;
4.1.1 0°
(3)
4.1.2 90°
(3)
4.1.3 180°
(3)
4.2 What wavelength does a hydrogen atom emit as its excited electron falls from the
n = 5 state to the n=2 state? Answer to three significant figures.
(7)
4.3 Compute the energy of a photon of blue light of wavelength 450 nm. Give your
answer in electron volt.
( 4)
QUESTION 5
[22 MARKS]
5.1 State one imp01tant idea that Plank used in other to obtain the correct spectral
distribution for the blackbody radiation. Write down the Plank spectra distribution
law in frequency space.
(4)
Modern Physics (MPH602S)
1st Opportunity November 2024
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5.2 Explain the Pauli Exclusion Principle.
(3)
5.3 Using Pauli Exclusion Principle determine the quantum numbers for the electrons
in the lithium atom (Z = 3) when the atom is in its ground state.
(6)
5.4 Show the expression for one-dimensional Schrodinger equation for a particle with
a definite energy E.
(3)
5.5 Consider the wave function 1./J(x=) A1eikx + A2e-ikx, where k is positive. What is
the energy? ls this a valid stationary-state function for a free particle?
(6)
END OF EXAMINATION QUESTION PAPER
Modern Physics (MPH602S)
1st Opportunity November 2024
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