C A R I B B E A N E X A M I N A T I O N S C O U N C I L

CARIBBEAN EXAMINATIONS COUNCIL REPORT ON CANDIDATES' WORK IN THE

SECONDARY EDUCATION CERTIFICATE EXAMINATION MAY/JUNE 2007

PHYSICS

Copyright ? 2007 Caribbean Examinations Council ? St. Michael, Barbados All rights reserved.

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PHYSICS GENERAL PROFICIENCY EXAMINATION

MAY/JUNE 2007

GENERAL COMMENTS

Ten thousand eight hundred and forty-seven candidates registered for the examination this year compared with 10,330 in June 2006. This represents an increase of 5% when compared with June 2006.

Candidates showed weaknesses in performing mathematical calculations and in understanding some concepts which are sometimes overlooked by teachers. The calculations involving the scientific notation are still presenting some candidates difficulty. Teachers are encouraged to have students competent in the use of the scientific notation.

Teachers are encouraged to deliver the syllabus in a complete manner rather than choosing a core of objectives. This examination is a critical building block for further study at the Caribbean Advanced Proficiency Examination (CAPE) and for university level courses.

Paper 01 ? Multiple Choice

The performance in this year's multiple choice paper has improved over that of June 2006. This year, the average score was 38.72 out of a possible 60, with a standard deviation of 11.49.

Question 1

Paper 02 ? Structured Questions

Data Analysis, Section A ? Physical Measurements and Units, Section C ? Thermal Physics

Performance Overall

The average mark for this question was 14.49 out of a possible 30 and the standard deviation was 7.43. Approximately 30 candidates scored full marks.

Areas of good performance

Part (b), plotting of the graph. Most candidates demonstrated a good display of plotting skills. Skills tested were labelling, using appropriate scales, plotting, drawing the best line, fine line and extrapolation.

Areas of weak performance

Part (f). A large number of candidates failed to realize that if the pressure is doubled, the volume is halved. Features of Line 2 were (i) x-intercept is the same as Line 1 and (ii) y-intercept is ?12 that of Line 1.

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General comments and recommendations: (a) It is expected that when asked to draw a diagram, it is also labelled. (b) The key criteria in determining the slope of a graph are

(i) a large triangle (ii) correct read offs (iii) calculation with units. (c) Candidates should be given adequate practice in graph skills before marking for School Based

Assessments. (d) Syllabus objectives assessed: C 1.9 (b), A 3.1, A 3.2, A 3.3.

Question 2 Section B ? Mechanics

Performance Overall The average mark was 6.53 out of 16. The standard deviation was 4.51. Approximately 280 candidates scored full marks. Areas of good performance Part (b) (iii), the calculation of the average speed of the car. Part (b) (iv), using the formula F = ma. Areas of weak performance The linking of b (i) to b (ii). This involved a drawing of how velocity changes with time but includes the identification of reaction time on the graph. Acceleration was taken by some candidates as average speed divided by time instead of change of velocity divided by time. There was also a misconception of velocity as being speed. General comments and recommendations (a) Teachers should ensure that candidates have a good understanding of the concepts of average

speed, velocity change, and per unit time. (b) There is a need to perform activities involving reaction time and plot associated graphs. (c) Syllabus objectives assessed: B 3.2, B 3.3, B 4.3.

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Question 3

Section B ? Mechanics and C ? Thermal Physics and Kinetic Theory

Performance Overall

The average mark for this question was 7.11 out of a possible 14. The standard deviation was 3.40 and approximately 100 candidates scored full marks.

Areas of good performance

Part (b) concerning energy conversion and loss, and part (c) the calculation of energy using E = MC0- .

Areas of weak performance

Part a (ii) ? Many candidates did not recognise that emission of radiation was the issue in this section.

Part d ? Many candidates wrote the wrong equation. Here E = mlv was the needed equation. In part (c) and (d) candidates are still being confused with scientific notation.

General comments and recommendation

Teachers should ensure that candidates, in their study of thermal physics, know that

(i)

shiny surfaces are poor emitters of radiation,

(ii)

a change of temperature in ?C and K carries the same value and

(iii)

candidates should pay attention to vocabulary, grammar and appropriate use of Physics

terms and symbols.

Syllabus objectives assessed: B 5.4, B 5.18, C 4.1, C 4.2, C 4.3, C 4.4, C 3.3, C 3.8.

Question 4

Section D ? Waves and Light

Performance Overall:

The average mark for this question was 7.11 out of a possible 16 and the standard deviation was 3.40 . Approximately 10 candidates scored full marks.

Areas of good performance

Section (c) (iv) and (v) of the question were generally widely known. Candidates appear to be familiar

with n =

Sin ^i Sin ^r

and n =

c v?

.

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Areas of weak performance

Section (a) and (b) presented difficulties for candidates. Teachers are encouraged to look at the history of physics and relevant theories concerning the wave-particle duality. Some candidates gave the properties of light instead of the two theories.

In Section (c) part (i); although simply asked to say that all light was reflected at C, they were explaining how and why total internal reflection occurs.

General comments and recommendations:

(a) The following content should be well internalised by candidates ?SS?iinn??00--?12 = 1n2 = ?vv?12 = ??12? and total internal reflection via the use of a light-pipe.

A hands-on approach to this topic is highly recommended.

(b) Syllabus objectives assessed: D 2.2, D 2.4, D 2.5, D 5.1, D 5.4, D 6.5, D 6.6.

Question 5

Section E ? Electricity and Magnetism

Performance Overall

The average mark for this question was 4.7 out of a possible 14 and the standard deviation was 2.59. Approximately 4 candidates scored full marks.

Area of good performance

Section (c) of this question was widely known. Most candidates knew the formula Q = it and the unit of charge ? the coulomb.

Areas of weak performance

Section (a) part (ii). This involved explaining why there is a net force of attraction. The response expected includes two statements: (i) negative attracts positive and attraction greater than negative ? negative repulsion. Part (iii) charging by contact was a difficult concept for some. Section (c) ? conversion of millisecond to second.

General comments and recommendations

(a) There is a need for more hands-on experiences in this area ? use of electroscopes. The need to discuss practical applications of lightning rods emphasizing the conducting path.

(b) Syllabus objectives assessed: E 1.1, E 1.2, E 1.3, E 1.4, E 1.5.

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