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MPH602S-MODERN PHYSICS-JAN 2020 |
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NAMIBIA UNIVERSITY
OF SCIENCE AND TECHNOLOGY
FACULTY OF HEALTH AND APPLIED SCIENCES
DEPARTMENT OF NATURAL AND APPLIED SCIENCES
QUALIFICATION: BACHELOR OF SCIENCE
QUALIFICATION CODE: 07BOSC
COURSE NAME: MODERN PHYSICS
LEVEL: 6
COURSE CODE: MPH602S
SESSION: JANUARY 2020
DURATION: 3 HOURS
PAPER: THEORY
MARKS: 100
SECOND OPPORTUNITY/SUPPLEMENTARY EXAMINATION QUESTION PAPER
EXAMINER(S) | DR ONJEFU SYLVANUS
MODERATOR: | PROF DIPTISAHU
PERMISSIBLE MATERIALS
Non-programmable Calculator
ATTACHMENT
None
THIS QUESTION PAPER CONSISTS OF 3 PAGES
(Including this front page)
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QUESTION 1
[20]
1.1 Explain the Rutherford’s Model of the atom and give two limitations
to the model.
(9)
1.2 What do you understand by photoelectric effect?
(3)
1.3 What is the kinetic energy and speed of an electron ejected from a sodium
surface whose work function is Wo = 2.28 eV when illuminated by light
of wavelength (a) 410 nm, (b) 550 nm? [Take h = 6.626 x 10-34 J; me =
9.1.x 107; 1eV=1.6x 107"].
(8)
QUESTION 2
[28]
2.1 Explain the ground state of an atom.
(3)
2.2 Calculate the energy of the ground state and 1% excited state of the hydrogen atom. (6)
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 10].
(11)
2.4 Determine the wavelength of an electron in meters that has been accelerated
through a potential difference of 100 V.
(4)
2.5 Calculate the de Broglie wavelength of a 0.20 kg ball moving with a speed
of 15 m/s.
(4)
QUESTION 3
[20]
3.1 Explain the Heisenberg uncertainty principle.
(3)
3.2 A electron moves ina straight line with a constant speed v = 1.10 x 10 © 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?
[Take n= 1.06 x 10 -*4].
(10)
3.3 A radioactive material has a half-life of 10 hours. What fraction of the original
radioactive nuclei will remain after 30 hours?
(7)
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QUESTION 4
[21]
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 the n= 6 to the n= 2 energy level according to the
Bohr model. [Take Rydberg constant, R= 1.0974 X 10’m"!].
(6)
4.3 Explain Zeeman Effect and state what does the effect confirms.
(3)
QUESTION 5
[11]
5.1 Show the expression of a wave function ofa particle in a state of definite energy.
(3)
5.2 Showed that the ratio of the number of atoms disintegrating per unit time to
the number of atom in the source at that time is equal to a decay constant A.
Also show that N = Nge~* where all symbols have their usual meaning.
(8)
END