CAPE Physics Unit 2 · May/June 2022 · Paper 2

21 questions and parts from this paper. Open one to see it in full, then practise it on Quelpr and get it marked against the mark scheme.

1. 1(a)(i)4 marksDraw a circuit diagram showing THREE resistors, R1, R2 and R3, placed in series connected to a power supply. On your diagram, label the voltages and the currents associated with EACH resistor and the power supply.
2. 1(a)(ii)6 marksUsing the diagram in (a)(i), derive the formula for the effective resistance of the THREE resistors in series.
3. 1(b)10 marksCalculate the current I_L through the variable resistor R_L, when R_L has a value of 30 Ω.
4. 1(c)(i)2 marksComplete Column 3 in Table 1.
5. 1(c)(ii)4 marksOn the grid provided in Figure 2 on page 9, plot a graph of I_L versus [1 + (R_L / 6)]^-1. Draw the line of best fit through the points.
6. 1(c)(iii)4 marksUse the graph in (c)(ii) to determine the value of I_E.
7. 2(a)4 marksDerive an expression for the current waveform, in the form I = I_p sin(ωt), when the device is operating at its rated current.
8. 2(b)7 marksSketch a graph of ONE cycle of the current waveform in (a), with axes labelled to show the values of the period and amplitude.
9. 2(c)(i)7 marksDetermine the MAXIMUM drift velocity of the charge carriers in the semiconducting cylinder if the number density of electrons is 3 × 10^17 cm^-3.
10. 2(c)(ii)2 marksState how the electron drift velocity obtained in (c)(i) would compare with the electron drift velocity in a copper slug of identical dimensions carrying the same current. Explain your answer.
11. 2(c)(iii)4 marksThe resistance of the semiconductor cylinder in (c) was measured and found to be 80 Ω. Calculate the resistivity of the semiconductor in ohmmeters.
12. 2(d)6 marksSketch and label BEFORE and AFTER diagrams to describe the formation of the depletion layer in an unbiased p-n junction.
13. 3(a)(i)2 marksDefine Activity and state the unit in which it is measured.
14. 3(a)(ii)2 marksDefine Decay constant and state the unit in which it is measured.
15. 3(a)(iii)2 marksDefine Half-life and state the unit in which it is measured.
16. 3(b)(i)7 marksCalculate the half-life of Iodine-123, in hours.
17. 3(b)(ii)2 marksDetermine the energy of this photon, in Joules.
18. 3(c)(i)4 marksComplete Column 3 and Column 4 in Table 2.
19. 3(c)(ii)4 marksOn the grid provided in Figure 3 on page 19, plot a graph of ln(N/N_0) versus time, t. Draw the line of best fit through the points.
20. 3(c)(iii)3 marksReadings are no longer reliable when they fall below 2100 counts per minute. Use the graph in (c)(ii) to determine the period of reliability for a sample that is prepared and delivered with a starting count rate of 3000…
21. 3(c)(iv)4 marksState TWO properties of a radioisotope which might make it suitable for use in nuclear medicine, giving an explanation in EACH case as to why that particular property makes it useful.