CAPE Physics Unit 2 · May/June 2021 · Paper 2

27 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)3 marksDescribe the procedure involved in storing a quantity of electric charge on an initially uncharged parallel plate capacitor.
2. 1(a)(ii)3 marksExplain the movement of charges in the procedure described in (a) (i).
3. 1(b)4 marksOn the grid provided in Figure 2 on page 7, plot a graph of the discharge current, I_D, versus time, t. Draw a smooth curve through the points.
4. 1(c)(i)4 marksThe time constant for the type of discharge curve obtained in (b) may be defined as the time taken for the current to decay to 1/e of its initial value (where e is Euler's number, the mathematical constant which is the…
5. 1(c)(ii)2 marksCalculate the value of the unknown capacitor in Figure 1.
6. 1(c)(iii)5 marksCalculate the charge on the capacitor before the switch is closed.
7. 1(c)(iv)5 marksThe capacitor consists of two metal plates separated by a layer of insulating material 0.5 mm thick and of dielectric constant 450. Determine the area of the plates.
8. 1(d)4 marksShow, by equating the work per unit charge in moving a positive test charge q from B to A, that E, the strength of the uniform field between A and B, is equal to the voltage gradient.
9. 2(a)6 marksState THREE major properties of an ideal operational amplifier and explain how EACH property manifests itself when the operational amplifier is placed in a circuit.
10. 2(b)(i)2 marksDraw a diagram of a non-inverting operational amplifier circuit, labelling all important currents and voltages.
11. 2(b)(ii)2 marksUse your diagram in (b) (i) to derive the relationship between input voltage and output voltage for the non-inverting operational amplifier circuit.
12. 2(b)(iii)2 marksA non-inverting operational amplifier circuit has a gain of 11. Suggest practical values for the resistors in your circuit in (b) (i) which will achieve this gain.
13. 2(b)(iv)3 marksOn the diagram in Figure 4, sketch the output waveform, labelling the maximum and minimum points.
14. 2(b)(v)2 marksState the values of the output at t = 2 ms and t = 14 ms.
15. 2(c)(i)8 marksConsider the case where a digital 1 is represented by 1 V and a digital 0 by 0 V. Complete Table 2 for the input-output characteristics of a 3-bit D/A converter.
16. 2(c)(ii)4 marksCalculate values for the resistors in Figure 5 such that the input-output characteristics of Table 2 would be realized.
17. 2(c)(iii)1 markState the MAJOR disadvantage of the circuit in Figure 5 when used as a D/A converter.
18. 3(a)(i)2 marksDetermine log₁₀R for EACH value of x and complete Row 3 of Table 3.
19. 3(a)(ii)3 marksUsing the axes provided in Figure 6 on page 17, plot a graph of log₁₀R against x, ensuring that the x-axis extends to x = 3.0 mm. Draw the line of best fit through the points.
20. 3(a)(iii)3 marksDeduce the count rate at x = 2.8 mm.
21. 3(a)(iv)2 marksExplain why the lower count rate values are more likely to be inaccurate.
22. 3(b)(i)4 marksDescribe the photoelectric effect and explain how the stopping potential is related to the kinetic energy of the ejected electrons.
23. 3(b)(ii)3 marksUsing the relationship between stopping potential, V_s, and maximum kinetic energy, show that v_max, the maximum speed of ejected electrons, is given by v_max = sqrt(2eV_s/m).
24. 3(b)(iii)2 marksCalculate the maximum velocity of the photoelectrons ejected from the metal surface.
25. 3(c)(i)4 marksDescribe how radiocarbon dating is used to determine the age of ancient organic materials.
26. 3(c)(ii)4 marksA radioactive isotope of carbon found in a sample of 6.02 × 10^23 atoms of living wood has a decay constant of 3.84 × 10^–12 s^–1. Calculate its half-life in years.
27. 3(c)(iii)3 marksCalculate the rate of decay of C-14 in this sample.