GCE Physics AS Examination Summer 2016 · Summer 2016 . GENERAL COMMENTS FROM PRINCIPAL EXAMINERS...

GCE Physics AS Examination Summer 2016

GENERAL COMMENTS FROM PRINCIPAL EXAMINERS • Questions on more familiar topics were answered considerably better than those on

new topics

• Candidates displayed good mathematical skills with the exemption of some careless mistakes

• Responses to questions assessing practical skills suggested some candidates had been more prepared than others

• Responses to both quality of extended response questions (QER) were well done

• Responses to the “issues” questions were generally well done

• Papers are marked on-screen. There are continuation pages at the back of each examination paper. If a candidate has to use the continuation page please ask them to clearly mark what question part their answer refers to.

AS Physics UNIT 1

Contact Details Liane Adams Biology Subject Officer 029 2026 5126 [email protected] Lowri Evans Subject Support Officer 029 2026 5140 [email protected]

Maximum mark = 80 Mean mark = 41.0 Entry = 2 282

A B C D E

Grade boundary

55 48 41 34 27

Cumulative % at grade

20.8 36.1 52.7 68.9 80.9

AS Physics UNIT 1

ITEM LEVEL DATA

All candidates performance across questions

Question N Mean SD Max mark FF Attempt %

1 2289 3.7 2.2 8 45.7 99.6

2 2278 6.5 2.9 10 64.6 99.1

3 2290 7.3 3.5 13 55.8 99.7

4 2294 5.8 2.7 12 48.4 99.8

5 2295 7.2 2.5 11 65.9 99.9

6 2288 5.0 3.0 12 41.9 99.6

7 2293 5.8 3.4 14 41.2 99.8

AS Physics UNIT 1


QUESTION 1 Practical skills question Apparent the candidates who had been well prepared. (a) Successful candidates used a variety of approaches to determine the % uncertainty in the density. Most candidates used the more conventional approach of adding the percentage uncertainty in each of volume and mass to determine the total uncertainty in density. A few candidates gave answers which were incorrect in terms of significant figures. (b) AO3 question - Vague and ambiguous reasons for their choices were not awarded the second mark in (i). For example, responses such as ‘because the uncertainty is large’ were not credited.

AS Physics UNIT 1


QUESTION 2 A familiar topic although previously tested on paper 2 (i.e. PH2) Generally well answered Mainly assessed AO1 Encourage candidates when using the conservation laws to clearly structure their answers

AS Physics UNIT 1


QUESTION 3 Mathematical slips occurred e.g.“ power of 10” slips when taking wavelength readings (a)(ii) and (b)(iii) parts requiring explanations needed more detail and information (b)(i) A significant minority misinterpreted the meaning of A and calculated either the cross-sectional area of both stars or, in some cases, their volumes. (b)(ii) Few candidates were able to calculate the intensity of the radiation reaching earth from Sirius A. Many candidates were unable to determine the surface area correctly.

AS Physics UNIT 1


QUESTION 4 Based on a specified practical. The information provided in the question was sufficient to enable candidates to answer the questions set regardless of what experimental technique they had experienced to determine the Young Modulus of a metal wire. (a) Mainly assessed AO3 Few candidates were able to recognise the fact that the test and reference wires were made from the same material and that, consequently, temperature change would have the same effect on both. The majority of candidates made incorrect reference to the common support. Few were able to explain how an experimenter would know whether or not the elastic limit had been reached in terms of loading and unloading.

AS Physics UNIT 1


QUESTION 4 ctd (b) Answered well by the majority. Common mistakes in (i) included: - calculating ‘A’ incorrectly - taking incorrect readings from the graph - providing a final answer to an inappropriate number of significant figures.

AS Physics UNIT 1


QUESTION 5 QER question Banded response mark scheme Responses in general were very good Better responses contained a sustained line of reasoning which was coherent, relevant, logically structured and covered nearly all of the relevant marking points. Weaker responses contained just a few of the key marking points and were generally unstructured and lacked coherence.

AS Physics UNIT 1

AS Physics UNIT 1


QUESTION 6 (a) Only a minority of candidates were able to distinguish between the

horizontal and vertical components of velocity of the projectile. Those candidates that were successful in describing the motion in both planes were unable to explain their answers in terms of the forces acting/not acting on the projectile.

(b) In part (ii) only a minority of candidates were successful in using an appropriate equation of motion to find the acceleration due to gravity on the comet. In many cases candidates incorrectly substituted the value of the horizontal component found in (i) into their chosen equation(s). (c) “Issues” question – generally well answered with some very good answers seen. Comments which did not expand on the bullet points were not credited. Assessed AO3.

AS Physics UNIT 1


QUESTION 7 (b) In part (i) a noticeable number of candidates misread the

momentum axis and were penalised one mark for a ‘power of 10’ slip.

(c) In part (i) only a minority of candidates stated Newton’s second law in terms of momentum as required. The majority of responses were based on ΣF = ma, either in equation form or in words.

Recognised as a correct form of the law, this approach did not answer the question as stated and no credit was subsequently awarded. Credit was awarded however for the ‘rate of change of momentum’ formulae with all terms being defined. The question was deliberately asked in this form in the hope that it would provide some guidance for candidates in parts (ii) and (iii).

AS Physics UNIT 2


Maximum mark = 80 Mean mark = 32.3 Entry = 2 288

A B C D E

Grade boundary

47 40 33 26 19

Cumulative % at grade

21.3 33.4 48.1 63.5 77.6

AS Physics UNIT 2

ITEM LEVEL DATA

All candidates performance across questions

Question N Mean SD Max mark FF Attempt %

1 2266 3.6 2.3 8 44.5 98.6

2 2279 5.1 3.3 13 38.9 99.2

3 2262 4.1 2.7 9 45.2 98.4

4 2277 3.9 2.1 9 43.6 99.1

5 2293 5.4 3.4 14 38.8 99.8

6 2262 3.0 2.6 10 29.8 98.4

7 2292 7.7 3.2 17 45.0 99.7

AS Physics UNIT 2


QUESTION 1 A familiar topic but with the eV present. Mainly assessed AO1. (a) Good answers for both parts. However common mistakes were to

omit or bungle the conversion from eV to J and to use level U’s energy as the photon energy.

(b) The second mark, not gained quite as often as the first mark, was for saying that level L is self-emptying or words to that effect.

AS Physics UNIT 2


QUESTION 2 (a) A familiar topic which was well answered.

(b) This was poorly answered. When, in the past, virtually the same question has been asked with numerical data supplied, candidates have fared better – despite the extra effort needed to produce a numerical answer. Part (iii) was generally answered correctly.

AS Physics UNIT 2


QUESTION 3 Again a familiar topic. (a) Answered well by the majority. (b) A common mistake in part (i), costing one mark, was to use 9° rather than 81. An angle other than 90°on the cladding side of the equation destroyed the logic, losing both marks. In part (ii) weaker candidates didn’t see that a trig ratio was needed. In part (iii) it was really pleasing to see how well candidates coped with a difficult question. The commonest mistake was to forget that the speed of light in a vacuum needed to be divided by n for the core.

AS Physics UNIT 2


QUESTION 4 (a) Derivation of the diffraction grating equation is a new arrival in the

specification. Few candidates drew and labelled the right-angled triangle on which the derivation hinges. (b) This part assessed practical skills. Only about half the candidates drew good graphs of sinθ against n, from the values of θ and n supplied. Sometimes poor scales were chosen or axes left unlabelled, but a surprisingly common mistake was to plot θ rather than sin θ. In part (ii) surprisingly few found the graph gradient and equated it to λ / d , but full marks were available for methods using a point from the graph line. This part assessed AO3.

AS Physics UNIT 2


QUESTION 5 The first few parts were answered well. (b) (iii) Many didn’t realise that the total energy dissipation called for the corresponding power to be emf × current, not terminal pd × current. This mistake cost 1 mark. (iv) Determining the new closed-circuit voltmeter reading when the 1.50 Ω resistor was replaced by 0.75 Ω was generally poorly done. (c) In part (ii) candidates quite often said that “the LDR’s resistance will

decrease so the voltmeter reading will go up”. This didn’t count as an explanation, since the LDR’s behaviour was given in the question.

As a general rule, an acceptable answer had to include some reference to the 100 W resistor! Many answers didn’t.

AS Physics UNIT 2


QUESTION 6 (a) Many candidates didn’t realised that they were dealing with

stationary waves. (b) In part (i) “half a wavelength out of phase” was not accepted. Finding the second wavelength was more elusive. In part (ii) a plan of action was required and it was good to see many well-argued answers.

AS Physics UNIT 2


QUESTION 7 (a) Practical skills assessment The drawing of the circuit diagram in part (i) was poor and not equivalent to the standard seen in previous PH3 papers. (b) The QER question was well answered. The point that the increase in resistance was due to the increase in (amplitude of) ionic vibration wasn’t made very often. Other misconceptions noted were that free electrons are vibrating, and that the link between increased resistance and increased temperature was somehow independent of all the stuff about ions and free electrons. (c) The “issues” question was also well answered. Assessed AO3.

CHANGES TO AS CONTENT Unit New Removed

1

• Momentum • Solids under stress (includes stress,

strain and Young modulus) • Multiwavelength astronomy added

to “using radiation to investigate stars”

• Reference to the p-p chain removed from “using radiation to investigate stars”

2

• Derivation of the diffraction grating formula • Electron volt, electron diffraction, de Broglie and radiation pressure added to the “photons” section

• Some charge statements removed from “conduction of electricity”

A2 UNIT 3: OSCILLATIONS AND NUCLEI Written Examination : 2 hours 15 minutes (100 marks) Content – Section A (80 marks) • Circular motion

• Vibrations

• Kinetic theory

• Thermal physics

• Nuclear decay

• Nuclear energy

Content – Section B (20 marks)

Comprehension question – this could be based on any of the specification content

A2 UNIT 4: FIELDS AND OPTIONS Written Examination : 2 hours (100 marks) Content - Section A (80 marks) • Capacitance

• Electrostatic and gravitational fields of force

• Orbits and the wider universe

• Magnetic fields

• Electromagnetic induction Content - Section B (20 marks) : one of the following four options • Alternating currents

• Medical physics

• The physics of sports

• Energy and the environment

CHANGES TO A2 CONTENT Unit New Removed

3

• Vibrations (simple pendulum added) • Nuclear energy (BE per nucleon vs

nucleon number curve added)

• Kinetic theory (Boyle’s law removed) • Nuclear decay (uses of radioisotopes

and biological hazards removed) • Nuclear energy (nuclear reactors

removed)

4

• Orbits and the wider universe (Higgs boson, Hubble constant and critical density added)

• Change to the options topics:

- Alternating currents

- Medical physics

- The physics of sports

- Energy and the environment

• Magnetic fields (definition of the ampere removed)

• Electromagnetic induction (rms values, mean power and the oscilloscope removed [added to the alternating currents option])

SYNOPTICITY

Learners’ understanding of the connections between the different elements of the subject and their holistic understanding of the subject is a requirement of all A level specifications. In practice, this means that some questions set in A2 units will require learners to demonstrate their ability to draw together different areas of knowledge and understanding from across the full course of study.

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GCE Physics AS Examination Summer 2016 · Summer 2016 . GENERAL COMMENTS FROM PRINCIPAL EXAMINERS...

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