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MPH602S - MODERN PHYSICS - 2ND OPP - JANAURY 2025 |
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nAml BIA UnlVERSITY
OF SCIEnCE AnDTECHnOLOGY
FacultyofHealth,Natural
ResourceasndApplied
Sciences
Schoolof Natural andApplied
Sciences
Departmentof Biology,
ChemistryandPhysics
13JacksonKaujeuaStreet T: +264612072012
Private Bag13388
F: +264612079012
Windhoek
E: dbcp@nust.na
NAMIBIA
W: www.nust.na
QUALIFICATION : BACHELOR OF SCIENCE
QUALIFICATION CODE: 07BOSC
COURSE: MODERN PHYSICS
DATE: JANUARY 2025
DURATION: 3 HOURS
LEVEL:6
COURSECODE: MPH602S
SESSION: 1
MARKS: 100
SECOND OPPORTUNITY/ SUPPLEMENTARY: 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
.3 :f·ft
This paper consists o!)rpages 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 - 31 kg
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
1.1 Calculate the values of a and b from the equation below
fl Na+ i H Z + i He
[20 MARKS]
(5)
1.2 Determine the de Broglie wavelength of electrons with a velocity of 1.0 x IO 3 m/s. (6)
1.3 Electrons are moving with a velocity of 4.0 x IO 6 mis.
1.3.1 What is the de Broglie wavelength of the electrons?
(5)
1.3.2 If these electrons had started from rest, through what potential difference would
they have had to be accelerated to attain the velocity?
( 4)
QUESTION2
[26 MARKS]
2.1 Explain the ground state of an atom.
(3)
2.2 Calculate the energy of the ground state and !st excited state ofthe hydrogen atom. (4)
2.3 Calculate the frequency and wavelength of the photon emitted when an electron
makes a quantum jump from the n = 3 state to the ground state of the hydrogen
atom. [Take h = 6.6 x 10- 34 Js; c = 3.00 x IO8].
(9)
2.4 Determine the wavelength of an electron in meters that has been accelerated
through a potential difference of 100 V.
(6)
2.5 Calculate the de Broglie wavelength of a 0.20 kg ball moving with a speed
of 15 mis.
(4)
Modern Physics (MPH602S)
2nd Opportunity/Supplementary January 2025 2
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QUESTION3
[20 MARKS]
3.1 Explain the Heisenberg uncertainty principle.
(3)
3.2 A electron moves in a straight line with a constant speed v = 1.10 x IO 6 m/s
which has been measured to a precision of 0.10%. What is the maximum
precision with which its position could be simultaneously measured?
[Taken= 1.06 x 10- 34].
(10)
3.3 A radioactive material has a half-life of IO hours. What fraction of the original
radioactive nuclei will remain after 30 hours?
(7)
QUESTION 4
[21 MARKS]
4.1 Using Pauli Exclusion Principle, explain and show why sodium (Z = 11) is the
next univalent atom after lithium.
(10)
4.2 Using Balmer series determine the wavelength of light emitted when a hydrogen
atom makes a transition from then= 6 to then= 2 energy level according to the
Bohr model. [Take Rydberg constant, R= 1.0974 X 107m-1].
(6)
4.3 Explain Zeeman Effect and state what does the effect confirms.
(5)
QUESTION 5
[13 MARKS]
5.1 Show the expression of a wave function of a particle in a state of definite energy.
(4)
5.2 Showed that the ratio of the number of atoms disintegrating per unit time to
the number of atoms in the source at that time is equal to a decay constant ,1..
= Also show that N N0 e-?tt where all symbols have their usual meaning.
(9)
END OF EXAMINATION QUESTION PAPER
Modern Physics (MPH602S)
2nd Opportunity/Supplementary January 2025 3