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MPH602S - MODERN PHYSICS - 1ST OPP - NOV 2022 |
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n Am I B I A u n IVER s I TY
OF SCI EnCE
TECH n
FACULTYOF HEALTH,NATURALRESOURCESAND APPLIEDSCIENCES
DEPARTMENT OF NATURAL AND APPLIED SCIENCES
QUALIFICATION: BACHELOROF SCIENCE
QUALIFICATION CODE: 07BOSC
LEVEL: 6
COURSE CODE: MPH602S
COURSE NAME: MODERN PHYSICS
SESSION: NOVEMBER 2022
DURATION: 3 HOURS
PAPER: THEORY
MARKS: 100
EXAMINER(S}
FIRST OPPORTUNITY EXAMINATION QUESTION PAPER
PROF ONJEFU SVLVANUS
MODERATOR: MR INDONGO VAINO
PERMISSIBLE MATERIALS
Non-programmable Calculators
THIS QUESTION PAPER CONSISTS OF 5 PAGES
(Including this front page)
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SECTION A
QUESTION 1
[40]
Multiple choice questions types: Each question in this section carries two marks
1.1 Which of the following representations is correct for an atom X with 28 electrons
and 30 neutrons?
(2)
a. 3zosx
C. s30sx
1.2 The energy associated with the emmited photon when a mercury atom changes
from one state to another is 3.3 eV. Calculate the frequency of the photon.
(2)
a. 8.0 x 10 14Hz b. 3.1x10 53Hz c. 1.3 x 10 -15Hz d. 3.2 x 10 -53Hz
1.3 In the Bohr's model of the atom, 'n' represents what?
(2)
a. angular momentum b. spin number
d. magnetic quantum number
c. principal quantum number
1.4 One of the following is not an application of photoelectric effect.
(2)
a. in burglar alarm b. in solar calculator c. in chromatiser
d. in television camera
1.5 A certain photoelectric surface is illuminated with light of various wavelengths
at various stopping potentials if the cut-off or threshold frequency of light is
4.6 x 10 14 Hz. Determine the threshold wavelength if the speed of light is given
by 3 x 10 8 m/s.
(2)
a. 1.38 xl0 23 m b. 6.5 x 10- 7 m c. 1.53 x 10 22 m d. 6.4 x 10- 6 m
1.6 .......... is a process that involves a photon given electron kinetic energy which
causes it to recoil.
(2)
a. Photoelectric effect b. Compton Effect c. Pair production
d. Recoil effect
1.7 A certain X-ray photon has energy of 6.2 keV. Calculate its frequency.
[Take h = 6.63 x 10- 34 Js; c = 3.0 x 10 8 m/s; leV = 1.6 x 10- 19 J].
(2)
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a. 1.5x10 18 Hz b.2.lxl0-
d. 1.2 X 10 -14 Hz
12 Hz c.2.0xlo- 10 Hz
1.8 What is the wavelength of the photon in Question 1.5?
(2)
a. l.4xl0 20 m b.2.5xl0 22 m c.l.5x10 18 m d.2.0xI0- 10 m
1.9 All the following are example of particle nature of light except ........ ..
(2)
a. Photoelectric effect b. X-ray production
d. black body radiation
c. polarization
1.10 There are four quantum numbers used to completely describe the structure
of all atoms which includes all the following except .................. .
(2)
a. continues number b. principal quantum number c. spin quantum number
d. magnetic quantum number
1.11 The spinning direction of two electron must be opposite to one another, it takes
the value;
(2)
1.12 The splitting of a spectral line by a magnetic field is known as;
(2)
a. Magnetic diploe moment b. Zeeman effect c. Stern-Gerlach experiment
d. Schrodinger effect
1.13 The actual dimensions of the nucleus present in the atom are called............
(2)
a. Nuclear density b. Nuclear size c. Nuclear force
d. Nuclear chain size
1.14 A process of formation of heavier and bigger nucleus by the combination of
various lighter and smaller nucleus.
(2)
a. A nuclear decay b. Nuclear fission
d. Strong nuclear force
c. Nuclear fusion
1.15 Suppose an atomic nucleus of element M undergoes positron decay. The
equation for this process can be written as.
(2)
a. p n + e+ + v
b. n p + e- + v
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c. p n + e+ +v
d. n p + e- + v
1.16 A deuterium nucleus and a tritium nucleus fuse together to form a helium
nucleus, releasing a particle X in the process, according to the equation
2
I
H
+
3
1
H
4
2
He
+X
which one of the following correctly identifies X?
(2)
a. Electron b. Neutron
c. Positron d. Proton
1.17 Who was the Scientist credited as the father of the atomic theory?
(2)
a. J.J Thomson b. E. Rutherford c. N. Bohr's d. E. Cloud
1.18 Which of the following is a pair of isotopes?
(2)
a. 3158A ran d 3156S
b·
35
17
Cl
and
37
17
Cl
c.
15
7
N
and
16
8
0
d· 3140s•1 an d 315op
1.19 What is the number of neutron in the uranium isotope 2ij~X?
(2)
a. 92 b. 146 c.238 d.330
1.20 The nucleon number and the proton number of a neutral atom of an element are
23 and 11 respectively. How many neutrons are present in the atom?
(2)
a. 11 b. 12 c.23
d.34
SECTIONB
QUESTION2
[20]
2.1 Explain the J.J Thompson' Model of the atom and give two limitation
to the model.
(9)
2.2 What do you understand by photoelectric effect?
(3)
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2.3 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 10-31; 1 eV= l.6x 10- 19].
(8)
QUESTION 3
[20]
3.1 Explain the ground state of an atom.
(2)
3.2 X-ray of wavelength 0.140 nm are scattered from a very thin slice of carbon.
What will be the wavelength of X-rays scattered at (a) 0°, (b) 90°, (c) 180°?
[Take h = 6.626 x 10- 34 J; me= 9.1 x 10-31; c = 3.00 x 10 8].
(9)
3.3 Determine the wavelength of an electron in meters that has been accelerated
through a potential difference of 100 V.
(5)
3.4 Calculate the de Broglie wavelength of a 0.20 kg ball moving with a speed
of 15 m/s.
(4)
QUESTION 4
[10]
4.1 Explain the Heisenberg uncertainty principle.
(3)
4.2 What is the unce1tainty in position, imposed by the uncertainty principle
on a 150 g baseball thrown at (93 ± 1) mph= (42 ± 1) mis?
(7)
QUESTION 5
[10]
5.1 Explain the half-life of a radionuclide.
(3)
5.2 The half-life of radioactive nucleus of 2 ~~Ra is about 1.6 x 103 years.
5.2.1 What is the decay constant (s-1) of 2~~Ra?
(7)
END
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