MINISTRY OF EDUCATION
FIJI SEVENTH FORM EXAMINATION
2009
PHYSICS
2.
FIJI MINISTRY OF EDUCATION
FSFE PHYSICS EXAMINATION REPORT 2009
1. Introduction
The 2009 FSFE Physics Examination had set out to test basic Form 7 Physics concepts, principles, and processes. The examination also contained problems that challenge the very able. In these aspects the test had achieved its objectives, although admittedly the sampling could have been more exhaustive. Complaints were made on the absence of any direct question on the Atomic Physics content of the syllabus. Other curious comments had been made on the presence of Form 6 content in the test. Ambiguities in some questions were quite fair, with relevant considerations made in the marking scheme in favour of candidates.
However, despite, these the paper on the whole proved to be a fair test in which candidates raw marks were on the whole better than the previous year’s. A sample of the raw marks shows an average of 45, with an approximate standard deviation of 17. The highest raw mark is 98 in Paper 1 and 40 in Paper 2. About 25% scored les than 30% in the paper and 25% scored above 63%. The facility of 0.42 shows that overall the examination is a fair test.
2. Section A (Multiple Choice, worth 30 marks)
The answers to the questions are given below in the table.
1 C 11 * 21 A
2 A 12 D 22 C
3 A 13 B 23 B
4 D 14 A 24 C
5 B* 15 D 25 A
6 B 16 C 26 C
7 C 17 A 27 D
8 D 18 D 28 C
9 D 19 D 29 D
10 A 20 C 30 B
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The mean mark for this section is 15.9, with a standard deviation of 9.0. The highest in the sample is 28 while the lowest mark is 5.
3 Section B (Short Answers, worth 30 marks)
Question B1
The question tests knowledge admittedly mainly of the previous year although it still is a test of candidate ability in Physics. Most scored marks because of the compensatory marking scheme.
(a) The marking scheme is sympathetic and many candidates scored marks here for sensible statements in the solution. Quite a few obtained the correct answer.
(b) Not well answered by candidates. Most show a complete lack of knowledge of the situation.
Question B2
This question is generally very well answered and candidates scored well for the physics knowledge shown in the solution. Many obtained the correct answer for the tension. A question well done by candidates.
Question B3
(c) One of the poorly answered questions. Many multiplied the values and obtained the correct answer.
(d) Surprisingly well answered by candidates. Most scored marks even just for writing ½mv2 in the working. The solution is made easier with a vector diagram comprising the centripetal and gravitational force vectors.
Question B4
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Question B5
The energy conservation associated with rolling bodies was obviously well studied and learned. Candidates scored very well in this question, with many scoring maximum marks.
Question B6
This is a question that hoped to test understanding of the basic properties of light particularly its velocity change when traveling in media. While content is encountered at the Form 6 level the basic principle of Snells law and the basic comprehension of refractive index still apply at the Form 7 course. On the whole the question, both parts (a) and (b, is done well only by the very able.
Question B7
(a) The question tested understanding of the effect of the motion on the wavefronts. Recall of the expression λ’ = (c-v)/f helped to obtain a wavelength of 0.58 m.
(b) Performance here showed much confusion of the various forms of the formulae relevant to the problem. It should be noted that the speed of sound to be used is that stated in the list of physical constants if this was not specifically stated in the problem. The good students recalled the correct form of Doppler’s formula and obtained the maximum marks.
Question B8
(a) Very well answered by candidates who obviously know Ohms Law well.
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Question B9
This question was on the whole poorly answered by candidates. Only the very able scored the maximum marks. Most were able to obtain the circuit current of 2.4 A in part (a) but could not recollect the expression for the energy stored in an inductor. The formula for the time constant for the current in an inductor was not well learned and most could not score in (b).
Question B10
The question tests understanding and applications of the principles involved in the motion of a charge in electric and magnetic fields – basic processes hat apply in atomic physics as well. Only well done by the very top 3% of candidates. Most are able to recollect the relationship between the magnetic and centripetal forces, but have completely ignored the accelerating impact of the electric field on the charge.
4 Section C ( 4 Questions at 10 marks each)
Question C1
(a) Despite the inconsistency between the values given and the dynamics of the situation candidates mostly scored well because they used correct formulae. It is pleasing to note that one candidate used the dynamics method and obtained full marks. In part (i) however, many candidates unnecessarily made work hard for them by their indiscriminate resort to formulae when the meaning of period would have led them to a simple division problem. Parts (ii) and (iii) were generally answered well. It is good to note that a few explained very well why the tension would be less.
(b) A simple application of gravitation concepts. Many candidates could not even apply Newton’s gravitation law to the situation. Most however scored well.
(c) This question was too difficult for most candidates. Only the very top 3% could solve the problem correctly. The main difficulty was the inability of candidates to calculate the time it took for the projectile to reach the fence.
Question C2
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(ii) The correct solution depends much on maintaining the sign of the momentum in the application of the conservation of momentum. (iii) Very well done.
(iv) Well answered by candidates
(b) Admittedly a question on basic hydraulics principle, there is nevertheless no satisfaction at this level in not being able to calculate the area of the circular cross-section. Very few could obtain the correct answer in (ii).
(c) Generally well answered. Many scored maximum marks. But many showed little knowledge of angular momentum or its conservation in such problems.
Question C3
The lowest mark for this question is ‘0’ while the highest is 10. The average mark obtained is 5/10.
(a) Satisfactorily answered. Many tried to solve the problem by using energy conservation and encountered great difficulty. Only about 5% obtained 5/5 in this part.
(b) Many did not even convert 37 oC to Kelvin temperature, or could not express 3 kHz as 3 x 103 Hz!
(c) Again many candidates showed an inability to recall relevant formulae to the physical situation or to convert correctly when using d = 1/N. But most however managed to score well in this question.
Question C4
(a) The question basically tested for understanding of the dynamics of the equality of the gravitational and the electric forces, as vectors, on the suspended charge. The resulting need of resolution of these forces in the required direction and the equality Eqcos 15 = mgsin 15 was understood only by the very able students. Generally poorly answered. Even conversion of grams to kg presented some difficulty!
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In part (ii) many used the electric potential energy formula for a point charge ignoring the uniform field between parallel plates. Parts (iii) to (v) were generally well answered by most candidates.
(c) Parts (i) and (ii) answers show that candidates have learned well the formulae for the current density and the drift velocity. Well done.
Question C5
(a) Diagrams for the shunt resistor were of many types but most candidates were able to score in (i). Calculation of the shunt resistance in (ii) was generally well done with many scoring full marks.
(b) Well answered by candidates.
(c) Kirchoff’s circuit laws on the whole seem to be well understood. Most scored well with the writing of the current and loop equations, but only the very able could solve these equations correctly. This was a part generally well done by candidates.
Question C6
(a) The solution is based on the equality of the magnetic and gravitational forces on the wire. The simple ensuing calculation and the application of the relevant hand rule for direction are correctly determined only by the very able candidates
(b) This is another question that was not answered well. While many obtained the correct answer of 54.4 V for part (i), the requirements for parts (ii) and (iii) are beyond most candidates. None obtained the correct time in (iii).
(c) Both parts of the question are generally well answered by most candidates, although far too many still cannot perform substitution processes correctly given the formulae.
Question C7
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(b) Part (i) was very poorly answered although it is a simple proportion test. Only about 4% were able to obtain the correct input power of 1.11 x 106 W. Candidates obtained marks in (ii) considering their answer to (i).
(c) Generally well answered, although many still cannot apply the appropriate hand rule for the current direction.
PAPER II
The examination tried to test the usual practical content in a Form 7 laboratory in Fiji. The marking scheme was very considerate of the candidates’ plight and students scored well in this examination compared to those of previous years. The highest mark was 40/40 and the lowest was 4.
Question I
(a) (i) Very well answered
(ii) Well answered but many could not round up the value and the uncertainty properly.
(b) Well answered but many could not round up the value and the uncertainty properly to have 31±3 cm3.
Question 2
(a) (i) Generally done well (ii) Well answered (iii) Well answered (iv) Not answered well
(b) The drawing of the line of worst fit was done well by most candidates. Determination of the uncertainty in the slope of the line is beyond the understanding or experience of most candidates. This important skill needs to be well practiced by candidates!
Question 3
(i) Very well done
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(iii) Most candidates obtained the full marks for this question, which has an inconsistency. The answer is 10 ms-2 but any candidate that showed reasonable working obtained the one mark for the question.
(iv) Well answered. The calculation is difficult and any determination of the PE or KE or statement of the energy conservation solicits a mark.
Question 4
(a) (i) Many candidates earned marks for basically writing a form of a = -kx but so many had no idea of what was required.
(ii) Well answered
(iii) Was not well answered as was expected. Most had no idea of the connection to SHM. Practical on this was probably not done!
(b) (i) Many candidates noted 0.4 but did not take he antilog to obtain he answer. Answered well only by the very able.
(ii) Many knew ‘n’ represents the slope but could not correctly determine its value.
Question 5
(i) Only answered well by the able candidates who were not daunted by the simple algebra of the angular equation θ = ωot + ½αt2.
(ii) Well done
(iii) The graph plot was generally well done
(iv) Very well answered
Question 6
(a) (i) Generally well drawn. Many had no idea of harmonics.
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(b) The determination of the extension was surprisingly well done by most, seeing that the spring constant needed to be calculated first. Many read off the graph. Well answered.
(c) Not well done by most candidates. Only about 2% obtained the full mark for this question.
Question 7
(i) Well answered and most obtained marks for this question.
(ii) The candidates who had experienced the experiment had answered this question quite well. Most had no idea showing lack of performance of such skills with the simple potentiometer and balance point determination.
(iii) Generally well answered with most scoring well in this calculation.
(iv) Well answered. Most scored maximum marks here.
Question 8
(a) (i) Not well answered as expected. A simple translation and interpretation of the chart is needed. Only the very able could get the answer correct.
(ii) Most scored on the basis of consistency with (i) above
(iii) This was too difficult for most, but the few (about 5%) top candidates could solve the problem.
(b) (i) The table was completed well by most candidates.
(ii) Many thought this was a step-down transformer
(iii) The gradient was well determined by most, but the efficiency concept is lost on the many.
