CAPE Physics Unit 2 · 2014 · Paper 2

31 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)1 markDefine the term 'capacitance'.
2. 1(a)(ii)1 markState the unit in which capacitance is measured.
3. 1(a)(iii)1 markIdentify the two SI units that comprise the unit for capacitance stated in (a)(ii).
4. 1(b)(i)2 marksCalculate the value of the voltage, V_A, when the switch, S, is in Position 1.
5. 1(b)(ii)3 marksUse your results from (b)(i) to calculate the value of the capacitance, C_A.
6. 1(b)(iii)2 marksShow that the two capacitors in series in Figure 1 are equivalent to a single capacitor of value 20\text{ }\mu\text{F}.
7. 1(c)(i)3 marksOn the grid provided on page 7, plot a graph of V_R against t for these results.
8. 1(c)(ii)1 markDraw the tangent to the curve at the point where t = 0.
9. 1(c)(iii)1 markHence, determine the time constant of the voltage decay.
10. 2(a)3 marksOn the grid provided, draw a fully labelled sketch of the reverse bias I-V characteristic of a typical silicon p-n junction diode.
11. 2(b)(i)3 marksComplete Column 3 of Table 2 by calculating \ln(I_D).
12. 2(b)(ii)5 marksOn the grid provided on page 11, draw a graph of \ln(I_D) vs V_D / V_T.
13. 2(b)(iii)4 marksUse your graph to calculate the reverse saturation current for this diode.
14. 3(a)5 marksWrite a brief description of an experiment to determine the half-life of a radioactive sample.
15. 3(b)3 marksState THREE properties of a radioisotope which would make it suitable for use in radiotherapy.
16. 3(c)2 marksCarbon-14, ^{14}_{6}\text{C}, is produced naturally in the upper atmosphere by neutron bombardment of atmospheric nitrogen, ^{14}_{7}\text{N}. Derive the nuclear equation for the natural production of carbon-14.
17. 3(d)5 marksCarbon-14 decays to nitrogen by beta emission with a half-life of 5730 years. Determine the percentage of carbon-14, relative to the initial amount, which would remain after 20 000 years.
18. 4(a)3 marksDefine the term 'electric field strength' and state the unit in which it is measured.
19. 4(b)2 marksTwo horizontal metal plates in vacuo are separated by 1\text{ cm} with a potential difference of 1\text{ kV} applied across them as shown in Figure 2. Calculate the electric field strength between the plates.
20. 4(c)(i)1 markA beam of electrons is projected through a hole in the positive plate with velocity v at an angle of 60^\circ to the plate. Describe the subsequent motion of the electron beam.
21. 4(c)(ii)4 marksCompare the motion of the electrons in the electric field with that of an object in the earth's gravitational field by considering the effect of the fields on the horizontal and vertical velocity components.
22. 4(d)5 marksWhat must be the value of v if the beam is to just touch the negative plate?
23. 5(a)4 marksDraw truth tables and the circuit symbols for the 2-input NAND gate and the XNOR gate.
24. 5(b)(i)2 marksDraw the NOR equivalent of the AND gate.
25. 5(b)(ii)1 markDraw the NOR equivalent of the OR gate.
26. 5(b)(iii)1 markDraw the NOR equivalent of the NAND gate.
27. 5(c)(i)3 marksShow, by using a truth table, that the circuit in Figure 3 produces the Exclusive NOR operation.
28. 5(c)(ii)4 marksHence, develop a circuit using NOR gates only which will provide Exclusive NOR operation.
29. 6(a)8 marksWith the aid of a CLEARLY LABELLED diagram, describe the way in which x-rays are usually produced for use in diagnostic medicine and dentistry.
30. 6(b)3 marksExpress the energies of x-ray photons of wavelength 10^{-11}\text{ metres} in electron Volts.
31. 6(c)4 marksThe absorption coefficient of x-rays in a hypothetical material is 0.3\text{ cm}^{-1} at the wavelength used in 6(b). What thickness of the material would be required to attenuate the intensity of a beam of x-rays to…