Nuclear and quantum physicsIB Physics HL: Topic test

20 questions, 54 marks

IB Physics HL

Nuclear and quantum physics topic test

Total 54 marks

Name

Class

Date

1
The nuclide nickel-60 (60Ni, nucleon number A = 60) and the nuclide uranium-238 (238U, nucleon number A = 238) are both stable or long-lived. The radius of a nucleus can be estimated using R = R0A^(1/3), with R0 = 1.2 fm.
(a)
What is the radius of a nickel-60 nucleus?
[1 mark]
A4.70 fm
B3.91 fm
C72 fm
D9.30 fm
(b)
Which statement about the nuclear densities of nickel-60 and uranium-238 is correct?
[1 mark]
AUranium-238 has a much greater density because it has more nucleons
BThey are approximately equal, because nuclear volume is proportional to nucleon number
CNickel-60 has a much greater density because it is smaller
DThe density cannot be estimated without knowing the binding energy
(c)
Show that the density of nuclear matter is of order 10^17 kg m^-3, using the radius of nickel-60 found in (a) and taking its mass to be 60u, where 1u = 1.66 x 10^-27 kg.
[2 marks]
Total for question 1: 4 marks
2
A clean potassium surface, work function 2.3 eV, is illuminated with ultraviolet light of wavelength 250 nm in an evacuated photocell.
(a)
What is the energy of a single photon of this ultraviolet light, in eV?
[1 mark]
A0.497 eV
B9.93 eV
C4.97 eV
D2.48 eV
(b)
What is the threshold frequency for photoelectric emission from this potassium surface?
[1 mark]
A2.78 x 10^14 Hz
B1.11 x 10^15 Hz
C3.47 x 10^14 Hz
D5.56 x 10^14 Hz
(c)
Calculate the maximum kinetic energy of the photoelectrons emitted from the potassium surface, in eV.
[2 marks]
Total for question 2: 4 marks
3
A sealed industrial source contains cobalt-60, which decays by beta-minus emission to nickel-60 with a half-life of 5.27 years. When manufactured, the source had an activity of 3.7 x 10^10 Bq.
(a)
Determine the decay constant of cobalt-60, and hence the number of cobalt-60 nuclei present when the source was manufactured.
[3 marks]
(b)
Calculate the activity of the source 10.0 years after manufacture, and state what fraction of the original cobalt-60 nuclei remain at that time.
[4 marks]
Total for question 3: 7 marks
4
In one possible spontaneous fission, a plutonium-240 nucleus (240Pu, 240 nucleons, binding energy 7.56 MeV per nucleon) splits into two fragments of equal mass number 119, each with binding energy 8.40 MeV per nucleon, together with 2 free neutrons.
(a)
Determine the energy released in this fission, using the binding energies per nucleon given, and explain why this energy appears as kinetic energy of the fragments and neutrons.
[6 marks]
(b)
Explain, with reference to the binding energy curve, why energy is released in the fission of heavy nuclides such as plutonium-240 but not in the fission of light nuclides such as carbon-12, and discuss one practical difficulty in sustaining a sold chain reaction using plutonium-240 rather than a fissile isotope such as uranium-235.
[6 marks]
Total for question 4: 12 marks
5
A star has a surface temperature of 12 000 K and a radius 5.0 times that of the Sun (solar radius = 6.96 x 10^8 m). The Stefan-Boltzmann constant is 5.67 x 10^-8 W m^-2 K^-4.
(a)
What is the luminosity of this star?
[1 mark]
A1.8 x 10^29 W
B1.4 x 10^28 W
C5.1 x 10^19 W
D1.0 x 10^17 W
(b)
In which region of the Hertzsprung-Russell diagram would this star be plotted?
[1 mark]
ALower right — cool and dim
BUpper left — hot and luminous
CUpper right — cool and luminous
DLower left — hot and dim
(c)
Explain how the radius of a star can be determined from its luminosity and surface temperature, without observing the star's disc directly.
[2 marks]
Total for question 5: 4 marks
6
A fission reactor operates at a constant power output of 1200 MW. Each fission of uranium-235 releases on average 200 MeV of energy (1 MeV = 1.602 x 10^-13 J), and the reactor is kept critical by inserting neutron-absorbing control rods.
(a)
Calculate the number of fission reactions occurring per second to produce this power output.
[3 marks]
(b)
Calculate the mass of uranium-235 consumed per day of operation at this power, and comment on why nuclear fuel needs to be replaced so much less often than the fuel in an equivalent fossil-fuel power station.
[4 marks]
Total for question 6: 7 marks
7
In a neutron diffraction experiment used to study crystal structure, thermal neutrons are cooled until their kinetic energy is 0.025 eV. The mass of a neutron is 1.675 x 10^-27 kg.
(a)
What is the de Broglie wavelength of these thermal neutrons?
[1 mark]
A7.8 x 10^-9 m
B7.2 x 10^-20 m
C1.8 x 10^-10 m
D2.6 x 10^-10 m
(b)
Which observation would provide direct evidence that these neutrons behave as waves rather than only as particles?
[1 mark]
AThe neutrons being deflected by an electric field
BThe neutrons losing kinetic energy in collisions with nuclei
CThe neutrons being absorbed by boron nuclei in a detector
DDiffraction of the neutron beam by the crystal lattice, producing a pattern of intensity maxima and minima
(c)
State and explain what would happen to the de Broglie wavelength of the neutrons if they were cooled further so that their kinetic energy decreased.
[2 marks]
Total for question 7: 4 marks
8
In the core of a star, two deuterium nuclei (2H, 2 nucleons each, binding energy 1.11 MeV per nucleon) fuse to form a helium-3 nucleus (3He, 3 nucleons, binding energy 2.57 MeV per nucleon) and a free neutron.
(a)
Determine the energy released in this fusion reaction using the binding energies per nucleon given, and calculate the corresponding decrease in mass.
[6 marks]
(b)
Explain, with reference to the binding energy curve, why this fusion reaction releases energy for the same underlying reason that the fission of plutonium-240 releases energy, and discuss one reason controlled fusion has not yet been achieved as a large-scale energy source on Earth despite it being how stars generate their energy.
[6 marks]
Total for question 8: 12 marks

End of questions