1.
State what is meant by the inverse-square law for gamma.
[1 mark]
- I = k/x²
JD SCIENCE
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.
Amira is asked about the inverse-square law for gamma in a AQA Physics paper.
(a) [2 marks]
- plot I vs 1/x²
(b) [3 marks]
- safety: inverse square + shielding
12.
Amira is asked about exponential decay in a AQA Physics paper.
(a) [2 marks]
- λ = ln2 / T½
(b) [3 marks]
- activity A=λN
13.
Amira is asked about binding energy in a AQA Physics paper.
(a) [2 marks]
- BE/A is greatest around iron
(b) [3 marks]
- fusion/fission release energy if BE/A increases
14.
Amira is asked about mass defect in a AQA Physics paper.
(a) [2 marks]
- u to kg
(b) [3 marks]
- 1 u is 931.5 MeV
15.
Amira is asked about nuclear fission in a AQA Physics paper.
(a) [2 marks]
- chain reaction, moderators, control rods
(b) [3 marks]
- waste is radioactive
16.
Amira is asked about nuclear fusion in a AQA 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.
Amira carries out a AQA-style required practical linked to nuclear physics. This is a typical AQA 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.
Amira carries out collecting valid data for nuclear physics. This is a typical AQA 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.
Amira carries out drawing a graph for nuclear physics. This is a typical AQA 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.
Amira carries out evaluating a method about nuclear physics. This is a typical AQA 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