1.
State what is meant by the inverse-square law for gamma.
[1 mark]
- I = k/x²
JD SCIENCE
Thermal and nuclear physics
Indicative marking points. Award marks for equivalent scientific or mathematical wording. Do not issue this sheet with the student worksheet.
2.
State what is meant by exponential decay.
[1 mark]
- N = N₀ e^{−λt}
3.
State what is meant by binding energy.
[1 mark]
- energy to separate nucleons
4.
State what is meant by mass defect.
[1 mark]
- Δm converted with E=Δmc²
5.
State what is meant by nuclear fission.
[1 mark]
- induced by a neutron in U-235
6.
State what is meant by nuclear fusion.
[1 mark]
- light nuclei join
7.
State what is meant by background radiation.
[1 mark]
- rocks, radon, cosmic, medical, nuclear
8.
State what is meant by safety.
[1 mark]
- time, distance, shielding
9.
State what is meant by the inverse square experiment.
[1 mark]
- measure count vs distance
10.
State what is meant by a decay chain.
[1 mark]
- series of decays to a stable isotope
11.
Jac is asked about the inverse-square law for gamma in a Eduqas Physics paper.
(a) [2 marks]
- plot I vs 1/x²
(b) [3 marks]
- safety: inverse square + shielding
12.
Jac is asked about exponential decay in a Eduqas Physics paper.
(a) [2 marks]
- λ = ln2 / T½
(b) [3 marks]
- activity A=λN
13.
Jac is asked about binding energy in a Eduqas Physics paper.
(a) [2 marks]
- BE/A is greatest around iron
(b) [3 marks]
- fusion/fission release energy if BE/A increases
14.
Jac is asked about mass defect in a Eduqas Physics paper.
(a) [2 marks]
- u to kg
(b) [3 marks]
- 1 u is 931.5 MeV
15.
Jac is asked about nuclear fission in a Eduqas Physics paper.
(a) [2 marks]
- chain reaction, moderators, control rods
(b) [3 marks]
- waste is radioactive
16.
Jac is asked about nuclear fusion in a Eduqas Physics paper.
(a) [2 marks]
- needs high T for electrostatic repulsion
(b) [3 marks]
- the process in stars
17.
A=λN. λ=0.010 s⁻¹, N=5.0×10¹⁸
[3 marks]
- Final answer: 5.0 × 10¹⁶ Bq
18.
T½=8.0 days. λ
[3 marks]
- Final answer: 1.0 × 10⁻⁶ s⁻¹ order (ln2/T)
19.
N/N₀ after 3 half-lives
[3 marks]
- Final answer: 1/8
20.
I₂/I₁ = (x₁/x₂)². x doubles, I
[3 marks]
- Final answer: quarters
21.
E=mc². 1.0×10⁻⁶ kg
[3 marks]
- Final answer: 9.0 × 10¹⁰ J
22.
Activity falls from 240 to 30. Half-lives
[3 marks]
- Final answer: 3
23.
Jac carries out a Eduqas-style required practical linked to nuclear physics. This is a typical Eduqas required-practical style question.
(a) [2 marks]
- Independent: the independent variable for this topic
- Dependent: the measured outcome
(b) [2 marks]
- keep all other variables constant
- so the test is fair / only one variable is changed
(c) [2 marks]
- repeat and calculate a mean / use a tighter method
24.
Jac carries out collecting valid data for nuclear physics. This is a typical Eduqas required-practical style question.
(a) [2 marks]
- Independent: a chosen factor
- Dependent: a quantitative measurement
(b) [2 marks]
- calibrated instrument
- so the test is fair / only one variable is changed
(c) [2 marks]
- systematic error from zero error
25.
Jac carries out drawing a graph for nuclear physics. This is a typical Eduqas required-practical style question.
(a) [2 marks]
- Independent: x-variable
- Dependent: y-variable
(b) [2 marks]
- same scale / same apparatus
- so the test is fair / only one variable is changed
(c) [2 marks]
- not drawing a line of best fit through the trend
26.
Jac carries out evaluating a method about nuclear physics. This is a typical Eduqas required-practical style question.
(a) [2 marks]
- Independent: method change
- Dependent: precision / accuracy
(b) [2 marks]
- same sample size
- so the test is fair / only one variable is changed
(c) [2 marks]
- too few repeats
27.
Compare the inverse-square law for gamma with exponential decay.
[4 marks]
- I = k/x²
- N = N₀ e^{−λt}
- give one linked difference
28.
Compare exponential decay with binding energy.
[4 marks]
- N = N₀ e^{−λt}
- energy to separate nucleons
- give one linked difference
29.
Compare binding energy with mass defect.
[4 marks]
- energy to separate nucleons
- Δm converted with E=Δmc²
- give one linked difference
30.
Compare mass defect with nuclear fission.
[4 marks]
- Δm converted with E=Δmc²
- induced by a neutron in U-235
- give one linked difference
31.
Apply your knowledge of background radiation to this situation: varies with location
[3 marks]
- varies with location
32.
Apply your knowledge of safety to this situation: ALARA
[3 marks]
- ALARA