MINISTRY OF EDUCATION
FIJI SEVENTH FORM EXAMINATION
2008
PHYSICS
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MINISTRY OF EDUCATION
FIJI SEVENTH FORM EXAMINATION 2008
PHYSICS
EXAMINER’S REPORT
GENERAL COMMENTS
PAPER 1
The 2008 FSF Physics Examination on the whole was a real test of the core Form 7 Physics
curriculum. It aimed to examine the student‟s understanding of basic concepts and principles, their ability to reproduce formulae important to the Form 7 Physics, and the ability to analyse situations and apply these principles and formulae in problem solving.
While there is adequate scope for an average candidate to pass the examination, there is also sufficient involvement that test the able students.
The examination statistics support the foregoing comments.
The paper was quite a difficult test.
The following general statistics relate to Paper 1 raw scores.
Number in sample - 230
% passed - 34.8%
Mean - 41.6
Range - 4 to 92
SECTION A
This selection contained 30 multiple-choice questions. Each was worth 1 mark.
In general this section was not done very well. Some students showed a lot of confusion in their choices as indicated by a lot of crosses over their initial choices. A handful of students made no choices at all on some of the multiple-choice questions. They should be encouraged to do so.
SECTION B
This section contained ten questions and all were compulsory. Each question was worth 3 marks.
A handful of candidates did not attempt this section at all.
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QUESTION 1
(a) This question was done very well. Most candidates recognised Ff μN or μmgCosθ.
(b) Many candidates had difficulty in recognizing that the system has 0 m/s2 and therefore motionless. Few candidates calculated acceleration as 0.039 m/s2 and 2.04 m/s2. However marks were awarded for the use of Ff, mgsin θ, total mass and gravitational force on the 4kg
mass.
QUESTION 2
Most candidates attempted to solve this problem. Many recognised that T = I = Tr =
r a
I while
some recognised 200 – T = 20a. Marks were awarded for these.
QUESTION 3
(a) This question was poorly done.
A handful of students realized that Tension (from part b) could be used to find the Reaction Force. Only a few candidates found the Reaction Force from 2000/Tan 34º.
(b) Well answered. A clear evidence of understanding of basic Trigonometry by the candidates who attempted this question.
QUESTION 4
This question was generally well done indicating that candidates had a good understanding of this type of projectile. A few students had interchanged vertical and horizontal components of the initial
velocity.
QUESTION 5
An average performance from most of the candidates. They were able to use the formula F= kx
correctly but had difficulty in writing the formula . k m 2
T Most students used
g 2
T l .
A few students had difficulty in conversions; g to kg; cm to m.
QUESTION 6
This question was very poorly done.
A handful of students were able to determine the correct wavelength using the formula c = f . Most students had difficulty in using the appropriate formula 2nt = (m + ½) to determine the minimum thickness.
Very few students were able to achieve full marks for this question.
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QUESTION 7
(a) This part was very poorly done. Many students only wrote
2 2 1 r q kq
F and did not go any
further.
Some had difficulty in recalling the formula above and ended up with
r q kq
F 1 2 or .
r kq
F 2
(b) This part was also very poorly done. However students had recognised that the resultant force was a vector sum of two forces. Partial marks were awarded for this.
QUESTION 8
This question was very well done indicating that the concepts on capacitor combination and wheatstone bridge were well understood by most of the students.
QUESTION 9
This question was generally poorly done. Most students failed to calculate the area correctly due to poor conversion from cm to m or from cm2 to m2. Partial marks were awarded for writing the appropriate formulae.
QUESTION 10
(a) Fairly done. Most students explained the Rutherford experiment and many did relate the model to spectra and radiation of energy by revolving electrons. The able candidates showed very satisfactory understanding of the Bohr Theory essentials.
(b) This question was well answered by most students who obtained at least a ½ mark for writing the relevant formulae.
SECTION C
There were seven questions in this section where any four questions were to be answered. Each question was worth 10 marks.
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QUESTION 1
This question was generally well answered from parts (a) to (b) (iii).
(b) (iv) Many candidates had written L = mvr = Iw correctly but substituted the wrong radius instead of 6.4 x 106 m.
(b) (v) The concept of momentum conservation in this part is notable. However, the calculation of the new period, T was a difficulty.
(c) Generally well done. However some students did not convert 900 nm to 900 x 10-9 m.
QUESTION 2
(a) Only a handful of students were able to score full marks in answering this question. Most students only answered as far as the calculation of P.E. after collision.
(b) (i) Generally well done.
(ii) Generally well done.
(iii) Many students failed to calculate the next two harmonics.
(c) Not well answered by many students who opted for question 2. This shows that the concept was not well understood by the students.
QUESTION 3
This question was very popular and well done by many of the students.
(a) (i) Very well answered.
(ii) Very well answered.
(iii) Majority of the students had difficulty in using the correct formula
m k
w but used
k m 2
T instead and their end result deviated a great deal from 504008 N/m.
(iv) Almost 99% of the students did not achieve full credit for this question. Most of the students were using x = A sin wt instead of x = A cos wt.
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(c) (i) Very well done.
(ii) A few students failed to use the appropriate formula for the velocity of wave, otherwise this question was well answered by most of the students.
QUESTION 4
Most of the students attempted this question scoring an average of 10
6
marks.
(a) Many students were able to recall the correct formula to be used but some substituted the speed of light (3 x 108 m/s) instead of the speed of sound (330 m/s or 340 m/s).
(b) (i) Very well done.
(ii) Poorly done. Most students repeated the working in part (i) above. This is time
consuming and it could be avoided by using the formulae
o d
C C
K .
(iii) Very well done.
(iv) Very well done.
(c) (i) Very well done. Most students have adequate knowledge of Kirchoff‟s first law.
(ii) Well done, but some students forgot to put V 0 around a closed loop. Some students lost marks by putting wrong signs for the potentials in the equation.
QUESTION 5
This question was also one of the popular questions in Section C.
(a) (i) Most students recalled the appropriate formulae but lost marks for not converting
10 mm to m.
(ii) Well done.
(iii) The able students answered this question with no difficulty at all. Most students failed to equate the two forces Fm = Fe to find the speed of the electron.
(iv) Well done but a few students did not indicate the directions.
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(b) Generally fairly done. Most students were able to write the appropriate formula but lost marks due to careless mathematical calculations.
(c) (i) Very well done. Almost all the students who answered this question had the correct answer.
(ii) Very poorly done. The most common wrong answer was I = 7A.
QUESTION 6
Generally not answered well with an average mark of 10
3 . 3
achieved by the candidates who attempted
this question.
(a) Far too many did not know the formulae needed for the question :
A R l,
R V P
2
and Area of Circle = r2
It is not satisfactory that Form 7 Physics students cannot recollect the correct formula for the area of a circle !
Average mark = 3
3 . 1
.
(b) For those who attempted this question, the difficulty was having the correct integration limits
for „dl‟ from 0 2 r. Average mark =
2 5 . 0
(c) Well answered by most students who attempted this question. Average mark = 5
1 . 2
(i) Well done.
(ii) Generally answered well.
(iii) Many students wrongly used the rms voltage in (i).
(iv) Most students had at least ½ mark in this question.
QUESTION 7
This question was not well answered, considering that basic knowledge is being tested in transformers
and photoelectricily. Average mark = 10
3 . 4
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(a) (i) Many students could not identify a step-up transformer.
(ii) Generally done very well.
(iii) The key word in the explanation is “induced” emf/voltage. Only a very few were able to use the term induced emf. Most of the students‟ responses to this question indicated that they lack the knowledge of this concept.
(iv) Generally well done. Some students could not recollect the relevant formula.
(v) Most students tried to explain why the generated emf has a negative value in terms of decreasing current when the relevant explanation is in Lenz‟s law.
(b) On the whole, the students‟ responses were rather disappointing as much is a review of FSLC work in photoelectricity, a topic still relevant in the Form 7 Physics course.
Average mark = 4
9 . 1
(i) Not answered well. Most students forgot about work-energy relation and tried to use ½ mv2.
(ii) The few who used the photo electric equation did well. Far too many were applying = hf indiscriminately.
(iii) Generally well done.
PART II
GENERAL COMMENTS
The 2008 FSF Physics Examination – Paper II tested the practical work outlined in the Seventh Form Physics course.
QUESTION 1
(a) (i) Very well answered by most students.
(ii) For too many do not relate r = ½ d.
(iii) Only the very able could determine the volume and its uncertainty correctly. Many did not know the formula for the volume of a cylinder.
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QUESTION 2
This question was generally answered well. Many candidates scored 5 3
marks in this question.
(i) Well answered. Some said “directly related” and many said they are in “response” when the simple response sought is “equal”.
(ii) Well answered by all.
(iii) Suprisingly well answered.
(iv) Many did not know the simple pendulum formula.
(v) Many types of graphs were observed when a hyperbolic relation is needed.
QUESTION 3
(a) Well done.
(b) Not answered well.
(c) Most had full marks on this question.
(d) Many had marks for writing more waves, greater frequency, smaller wavelength, smaller amplitude, etc.
(e) Too difficult for most but the very able students calculated correctly.
QUESTION 4
(i) The simple reason is to make the time interval a wholesome 0.1 second, which many mentioned. Those who wrote “to reduce errors” were awarded marks.
(ii) The candidates‟ inability to fill the table showed lack of practical experience. Only the very able top 5% could answer this part correctly.
(iii) Generally well done.
(iv) Most did not mention “simple harmonic motion”, which is all that is needed as an answer.
QUESTION 5
(i) Well answered.
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(iii) Well answered.
(iv) Well answered.
(v) Only about 1% could deduce the relation P = 3.2 Q4.2.
QUESTION 6
(a) (i) Well answered by most. Some mentioned “inertia” which is not correct.
(ii) The graph was well drawn by most although many make the line pass through the origin.
(iii) Well answered.
(iv) Well answered.
(b) (i) Well answered.
(ii) The information is inconsistent but answeres of 0.1 J or 0.45 J were accepted. All who attempted had ½ marks.
QUESTION 7
(a) (i) Very few mentioned the current safety control aspect of the resistor R.
(ii) Well answered.
(iii) Well answered. Many had no idea of the potentiometer relation of emfs and lengths.
(b) (i) Very well done.
(ii) Only the very able could give a half-life of around 45 – 55 years. Most divided the 180 years by two !
QUESTION 8
(a) (i) Well done by many. A real test of Physics IQ.
(ii) Not answered well.
(b) (i) Well answered.
(ii) Well answered.
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(c) This straight forward phasor practical exercise is not understood by most. Only about 3% were able to draw the supply voltage phasor correctly.
