CAPE Physics Unit 2 · 2005 · Paper 1

47 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 markExplain what is meant by the 'drift velocity' of charge carriers.
2. 1(a)(ii)4 marksFigure 1 shows a current i flowing through a length of wire L with cross-sectional area A, containing n charge carriers per unit volume, with average drift velocity v_d and charge q on each carrier. Show that the drift…
3. 1(b)(i)2 marksCalculate the number of electrons passing through the wire each second.
4. 1(b)(ii)3 marksCalculate the drift velocity of the charge carriers in the salt solution.
5. 2(a)(i)a)1 markWrite an expression for the electric field at B.
6. 2(a)(i)b)1 markWrite an expression for the electric potential at B.
7. 2(a)(ii)1 markShow how the electric field and electric potential at B are related.
8. 2(b)(i)1 markExplain why the uncharged sphere is attracted to the positive plate.
9. 2(b)(ii)3 marksExplain why the sphere subsequently oscillates between the plates.
10. 2(b)(iii)3 marksWhen the ball is not touching either plate, the force on the ball is 0.05 N. The plates are 10 cm apart and the supply voltage is set to 1 kV. Calculate the charge on the sphere.
11. 3(a)(i)1 markState Faraday's law of electromagnetic induction.
12. 3(a)(ii)1 markState Lenz's Law.
13. 3(b)2 marksGiving an example, explain how Lenz's law can be considered as an application of the law of conservation of energy.
14. 3(c)(i)2 marksCalculate the magnetic flux through each turn of the coil.
15. 3(c)(ii)2 marksIf the electromagnet is turned off and it takes 0.20 s for the field to go down to zero, what would be the e.m.f. induced in the coil of wire?
16. 3(c)(iii)2 marksState TWO reasons why transformers are NOT usually 100 per cent efficient.
17. 4(a)3 marksState THREE properties of the ideal operational amplifier (op - amp).
18. 4(b)(i)2 marksCalculate the positive and negative input voltages at which saturation will be reached.
19. 4(b)(ii)1 markA signal with voltage V_i given by V_i = 0.2 sin(100 pi t) is applied to the comparator in (b)(i). Calculate the frequency of the signal.
20. 4(b)(iii)4 marksOn the axes provided, sketch both the input voltage V_i and the output voltage V_o for TWO complete cycles, clearly indicating maximum voltages and periodic times on the axes.
21. 5(a)(i)2 marksSketch the I-V characteristic curve for such a diode.
22. 5(a)(ii)1 markExplain what is meant by the depletion layer at a pn junction and indicate this layer on Figure VI.
23. 5(a)(iii)a)1 markIndicate on Figure VI the direction of the diffusion current by labeling an arrow with an X.
24. 5(a)(iii)b)1 markIndicate on Figure VI the direction of the drift current by labeling an arrow with a Y.
25. 5(a)(iv)2 marksThe switch in Figure VI is now closed. Describe how the depletion layer is affected and explain the effect.
26. 5(b)3 marksFor each circuit in Figure VII, (ii)-(iv), sketch the output voltage as seen on the cathode ray oscilloscope on the axes beside the circuit diagram.
27. 6(a)(i)2 marksList TWO general areas in which digital electronics is commonly employed.
28. 6(a)(ii)1 markWrite down the truth table for the EXCLUSIVE-OR (X-OR) gate.
29. 6(a)(iii)1 markExplain how an X-OR gate can be used to detect when TWO binary digits are different.
30. 6(b)(i)2 marksComplete the truth table to show the outputs at Y and Z.
31. 6(b)(ii)3 marksSketch, in the space provided in Figure VIII, the output waveform at X, Y and Z if the input waveforms A and B are as indicated.
32. 6(b)(iii)1 markWhat single logic gate is equivalent to the circuit in Figure VIII?
33. 7(a)3 marksSketch the typical intensity-wavelength X-ray spectrum for molybdenum, clearly indicating the minimum continuous X-ray wavelength, lambda_min, and the characteristic peaks in intensity.
34. 7(b)2 marksExplain the origin of the characteristic peaks observed in your sketch in (a).
35. 7(c)3 marksOne of the K-shell electrons is removed from the atom by electron bombardment and its vacancy is filled by an M-shell electron. Calculate the wavelength of the emitted X-rays.
36. 7(d)2 marksThe tube is operated from a 25 kV supply. What is the minimum wavelength of the continuous spectrum of X-rays?
37. 8(a)(i)1 markExplain what is meant by half-life when referring to a radioactive source.
38. 8(a)(ii)1 markExplain what is meant by decay constant when referring to a radioactive source.
39. 8(b)(i)3 marksCalculate the decay constant of Radium-226.
40. 8(b)(ii)2 marksThe sample contains 5.0 x 10^16 such nuclei at t = 0. Calculate its activity at this time.
41. 8(b)(iii)3 marksCalculate the decay rate when the sample is 2.5 x 10^3 years old. [Data: 1 year = 3.2 x 10^7 s]
42. 9(a)(i)3 marksBeside EACH letter write the name of the parts labelled Q, S and T in Figure X.
43. 9(a)(ii)1 markDescribe the principle of the operation of a G-M tube.
44. 9(a)(iii)2 marksExplain why a mixture of argon and bromine gas is used in the tube.
45. 9(b)(i)1 markIdentify the type of radiation recorded at position A.
46. 9(b)(ii)1 markShow on Figure XI the region where gamma radiation would be detected.
47. 9(b)(iii)2 marksIf the distance from the source to the Geiger-Muller tube is about 15 cm, alpha-particles cannot be detected. Explain why.