MINISTRY OF EDUCATION
FIJI SEVENTH FORM CERTIFICATE
EXAMINATION
2011
PHYSICS
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MINISTRY OF EDUCATION
FIJI SEVENTH FORM CERTIFICATE EXAMINATION 2011
PHYSICS
EXAMINER’S REPORT
GENERAL
A total of 1705 candidates sat for the 2011 Physics paper. This number shows an increase of 300 candidates when compared to 2010.
Candidates were examined on the following topics: Mechanics, Gravitation, Direct Current, Electrostatics, Simple harmonic motion, Travelling waves, Magnetism, Electromagnetism and Atomic Physics. The examination tested mainly on knowledge, application and analysis of Physics concepts learned in the syllabus. The examination, though fair in its content and student friendly, posed many challenges to many candidates. The examination revealed challenges in both the theory and practical papers.
The following comments are general on the various sections of the examination.
A good number of candidates scored well. Such scores demonstrated good command of the subject matter by them. Poor performance of candidates may be attributed to insufficient understanding of the concepts tested.
A random sample was selected for analysis purposes. The following weaknesses have been noted:
(i) Many candidates had difficulty with converting of units to SI units. Many candidates failed to realize that formulas used in Physics require quantities expressed in SI units.
(ii) Many candidates recalled formula correctly but did poorly in the application.
(iii) Questions which required the use of vectors were done poorly. Knowledge of vector and scalar quantities was lacking.
(iv) Writing of answers in standard forms is an area needy of improvement.
(v) Experimental procedures and application of concepts need to be understood well especially for Paper II. Practical work was essential in order to make the concepts understood by candidates.
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PAPER 1
SECTION A
There are 30 multiple choice questions.
The analysis of responses in percentage taken from a random sample of 100 scripts is tabulated below. The correct response for each number is marked with an asterisk (*).
Question A B C D Question A B C D
1 21 20 20 39* 16 18 22 11 49* 2 20 14 54* 12 17 47* 17 21 15 3 23 15 22 40* 18- 43 28* 13 16 4 24 21 25 30* 19 34* 29 21 16 5 11 46* 27 16 20 43* 18 15 24 6 24 30* 21 25 21 25 21 27* 27 7 24 22 16 38* 22- 9 17 36 38* 8 11 24 41* 24 23- 31 26 15 28* 9 27 14 17 42* 24 54* 14 17 15 10 27 15 42* 16 25- 22 25 24* 29 11 29 9 22 40* 26 12 12 24 52* 12 16 17 34* 33 27 16 26 35* 23 13 15 33* 32 20 28- 19 24 32 25* 14 33* 15 22 30 29- 28 30 21 21* 15 13 47* 28 12 30- 20 16 33 31*
Sound knowledge of Physics was required for candidates to make the correct choices. This was clearly illustrated with the percentages shown above for each of the questions. The distractors were very effective hence the illustration above for this section. Questions 18, 22, 23, 25, 28, 29 & 30 proved to be challenging to most candidates.
SECTION B
The 10 questions in this section carried 3 marks each.
Q1. Candidates did very poorly. F= ma was a common approach instead of τ = Fd. The tower is symmetrical at 50 m as given in the illustration. Concept of moments was not understood. Resolution of forces acting on the tower and vector addition was not realized by most candidates.
Q2. Generally, this question was well done. Many candidates knew Σ F = ma. Similarly for part (b), Σ F = ma is used however, a, is negative in its application.
Q3. Part (a) was done well with the equation F = BILSinθ. The difficulty lies with the direction of the force. On part b) many candidates did not know that τ = BANI Cos θ and Cos 0 = 1 to give a maximum torque.
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Q5. Formula for Period (T) was used correctly in most cases however, the use of the T to determine ω was the challenge. The ω was to be used to calculate total energy for part (b) and later used again to determine the potential energy for the system applying the total energy concept. Et = Ep + Ek
Q6. Common mistakes included the use of appropriate formula with the incorrect constant, k. Vector addition was lacking in many cases.
Q7. Area and distance conversions were found to be difficult for some candidates. The question was generally well done.
Q8. Responses from candidates clearly showed the concept on wedges was not well understood by them. Prefix nm and conversion of mm to m need to be taught more thoroughly.
Q9. Many candidates could not recall Balmers formula correctly. Many of them did not know that transitions are for n ≥ 3 to n = 2. The shortest λ occurs when transition is from infinity (α) to n = 2.
Q10. Calculations of Rs were generally easy. Candidates did well drawing Part (b). Obsolete
symbols were used by many candidates. Teachers need to teach appropriate symbols for the electrical devices.
GENERAL COMMENTS ON SECTION C
C1. (a) Conversion from rev/s to rad/s was a concern. Most candidates recalled the conservation of angular momentum correctly, Li = Lf
(b) Formulas were recalled correctly however, conversion from mm2 to m2 was not done by many candidates prior to use of the equations. Part (iii) in particular required candidates to firstly calculate the Volume of the copper wire and then determine the number of electrons in that volume.
(c) Candidates did generally well in this section. Modern physics has been taught well. (d) Polarization concepts was not well understood by many Candidates.
C2. (a) Generally well done.
(b) Calculation of total capacitance in series was well done as well as the calculation of Capacitor charge and Capacitor energy.
(c) The question was generally well answered. The vocabulary for the physics topic needs to be taught thoroughly by teachers.
C3. (a) Concept of circular motion was used. The determination of the angle θ and the resolution of vectors on an inclined plane proved to be challenging for many candidates.
(b) Concepts were well understood by candidates.
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C4. (a) Calculation of momentum was easy for most of the candidates. Application of Pythagoras theorem to determine the resultant vector was lacking in many
calculations. Concept of momentum conservation was applied and in some cases the desired velocity could not be calculated correctly because the initial momentum was not correct.
(b) Kirchoff’s law was well understood and applied.
(c) This was a question quite challenging to candidates especially the determination of the unknown C.
C5. (a) Most candidates wrote the correct formula but failed to use the distance as
(R + 320 km) in their calculations. Some candidates did not convert km to SI unit. For part (ii) marks were gained through consistency marking.
(b) Electric fields were calculated but were not treated like vectors in some scripts. Potentials were calculated and should be treated as scalar quantities.
(c) Well done by candidates as most of them remembered c = f λ. Parts (ii) and (iii) were poorly done. Soap film concept needs to be taught thoroughly in lessons.
C6. (a) Calculation of angular acceleration and Inertia were well done.
(b) The work on travelling waves were well understood. Many candidates scored full marks in this section.
(c) Calculation of impedance and current was very well done.
C7. (a) The whole calculation was based on Σ F = ma. Many candidates did not demonstrate understanding that Ff = Fn cos θ. In order to calculate system acceleration, the system mass must be used in the calculation. Candidates were expected to resolve the forces acting on the mass on the inclined plane. In order to calculate the Tension in the system, one of the masses need to be isolated.
(b) This was very well done by candidates.
(c) Generally well done. The components of velocity were calculated. Parts (i) and (ii) were easily done. Most candidates scored well in these two parts. Very few students scored full marks for part (iii).
PAPER II
The examination revealed concerns for practical skills. Understanding of physics concepts warrants hands on experiences and assistance from teachers.
Q1. (a) Calculation of percentage errors, absolute errors and significant figures badly need attention. Teachers need to spend more time teaching the basics of Physics.
(b) Skills for reading measuring instruments need to be taught more thoroughly.
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(b) It was evident from the type of answers received that concepts relating to the experiment were not thoroughly understood by candidates.
Q3. (a) Explanation and significance of the graph for the experiment was not well known to many candidates.
(b) Determination of a slope of a curve and graphical interpretation were skills most candidates did not display in this question. Teachers must take time to teach these skills.
Q4. (a) Slope of graph representing angular acceleration (α ) and area of graph representing angular displacement and relating α to linear acceleration (a) was well understood by many candidates.
(b) Generally, it was well done. However, graphical interpretation was a skill that many teachers need to work on with their students.
Q5. (a) Generally well done. Graphical interpretation and the significance of the graphs were key skills to candidates scoring in this question.
Q6. (a) (i) – (iv) were very well done.
(b) Many candidates did not know the analysis of a ticker-timer tape. Candidates are required to be able to analyze a ticker timer tape for velocity and acceleration.
Q7. (a),(b) The area under the graph represented work done. From the given graph, the spring constant was to be calculated and then substituted in the equation E = ½ k x2 . Many candidates were able to determine the energy and equate the energy to ½mv2 for velocity.
(c) Candidates were required to manipulate the formula for reactance Xc and using I = V / Xc predict the brightness of the bulb. Candidates were required to have knowledge of phasor diagrams. Some candidates failed badly when manipulating formulas and making predictions.
Q8. (a) The significance of time constant (τ ) was not understood by many candidates. (b) The µ was easily calculated. Parts (ii) and (iii) were generally well done.
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