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MPH602S - MODERN PHYSICS - 2ND OPP - JAN 2023 |
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nAm I BIA un IVERSITY
OF SCIEnCE Ano TECHnOLOGY
FACULTYOF HEALTH,APPLIEDSCIENCESAND NATURALRESOURCES
DEPARTMENT OF NATURAL AND APPLIED SCIENCES
QUALIFICATION: BACHELOROF SCIENCE
QUALIFICATION CODE: 07BOSC
COURSE NAME: MODERN PHYSICS
LEVEL: 6
COURSE CODE: MPH602S
SESSION: JANUARY2023
DURATION: 3 HOURS
PAPER: THEORY
MARKS: 100
SUPPLEMENTARY /SECOND OPPORTUNITY EXAMINATION QUESTION PAPER
EXAMINER(S) PROF ONJEFU SYLVANUS
MODERATOR: MR INDONGO VAINO
PERMISSIBLE MA TERIALS
Non-Programmable Calculator
THIS QUESTION PAPER CONSISTS OF 4 PAGES
(Including this front page)
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Physical Constant
Electron mass
Proton mass
Planck constant
Speed of light
leV
m" = 9.l lxl0- 31 kg
m" =1.6736xl0- 27 kg
h = 6.626 X 10-341
c=3xl0 8 m/s
1.6 X 10- 19
QUESTION 1
[18]
1.1 Explain the electron-cloud model and which region the cloud is being dense
and more diffused.
(6)
1.2 Explain the term excitation energy.
(2)
1.3 The figure below gives the energy level for mercury atom:
0eV
- 1.6 eV
- 3.7 eV
- 5.5 eV
- 10.4 eV
If a bombarding electron has energy 6.7 eV,
1.3.1 To what level will the mercury atom be excited?
(3)
1.4 What will be that wavelength of the light emitted if the mercury atom
drops from this excited state to the second level? [Take h = 6.626 x 10 -341;
c = 3 x 10 8 m/s].
(3)
1.5 Show that the photon in a 1240 nm infrared beam have energies of 1.00 eV.
(4)
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QUESTION 2
[20]
2.1 Define work function.
(2)
2.2 The work function of sodium metal is 2.3 eV. What is the longest wavelength
light that can cause photoelectron emission from sodium?
(6)
2.3 Calculate the minimum wavelength of X-rays when a voltage of 40 kV is
applied to the X-ray tube.
(4)
2.4 An electron falls from rest through a potential difference of 100 V. What
is its de Broglie wavelength?
(8)
QUESTION 3
[21]
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 a0.20kg.
(4)
3.1.2 an electron.
(4)
3.1.3 a proton.
(4)
3.2 Explain a blackbody and a blackbody radiation.
(3)
tc 3.3 The isotope 1 has a half-life of 5730 years. If at some time a sample contain
1.00 x 1022 carbon-14 nuclei, what is the activity of the sample?
(6)
QUESTION 4
[20]
4.1 Using Compton Effect: X-rays ofwavelength 0.140 nm are scattered from a thin
slice of carbon. What will be the wavelengths of X-rays scattered at;
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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
[21]
5.1 State one important 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)
5.2 Explain the Pauli Exclusion Principle.
(2)
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? Is this a valid stationary-state function for a free particle?
(6)
END
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