GCE PHYSICS B. PHYB2 Physics keeps us going Report on the Examination June Version: 1.1

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1 GCE PHYSICS B PHYB2 Physics keeps us going Report on the Examination 2455 June 2014 Version: 1.1

2 Further copies of this Report are available from aqa.org.uk Copyright 2014 AQA and its licensors. All rights reserved. AQA retains the copyright on all its publications. However, registered schools/colleges for AQA are permitted to copy material from this booklet for their own internal use, with the following important exception: AQA cannot give permission to schools/colleges to photocopy any material that is acknowledged to a third party even for internal use within the centre.

3 General Comments The question paper as a whole seemed to allow all candidates the opportunity to demonstrate their knowledge and understanding of physics. The paper seemed to be of the appropriate length with the vast majority of candidates able to attempt all questions. Higher achieving candidates answered the calculations questions in a manner that was well laid out and easy to follow; their logic was clear and contained few errors. On the other hand, lower achieving candidates had workings that lacked structure and were often too superficial for AS level. Lower achieving candidates appeared to be put off by the contextual nature of the questions and had a limited grasp of the topics. They often failed to extract the pertinent information and therefore could not begin to apply this to solving the problem. These candidates would significantly improve their performance by beginning calculations with a summary of the data (taking heed of units and prefixes) and identifying the quantity to be determined, and then use the Data and Formulae booklet to identify appropriate formulae and transcribe these correctly into the answer space. Substitution of the data before rearranging is a good way of ensuring the scoring of the first mark as there is less chance of an error occurring. Explanations and definitions also highlighted the gap between those candidates who have successfully made the transition from GCSE and those not rising to the challenge of AS physics. Many lower performing candidates had failed to suitably prepare and demonstrated a limited ability to recall physics principles and definitions. There was evidence of lack of maturation in their written communication with many only able to make superficial statements. Higher performing candidates were able to produce coherent, detailed answers that demonstrated a thorough understanding of the underlying physics being examined in the various contexts. Question 1 The calculation was well done by the majority of the candidates. Parts (b) and (c) posed a greater degree of difficulty. A common misconception was that pumped storage was non-renewable because the useful output energy was less than the input energy. Others thought pumped storage was non-renewable because water was a limited resource. Part (c) was often answered from a load balancing perspective without describing the aspect of the pumped storage system that made it practicable to meet peak demand. Question 2 This question proved difficult for all but the best candidates. There were many misconceptions with most candidates unable to distinguish between acceleration and velocity. Most candidates stated that because the ball stopped at point B it had no acceleration. Other candidates realised that the acceleration was 9.8 ms -2 but were confused as to its direction or sign. Candidates failed to appreciate that acceleration is a vector quantity that is always in the same direction as the resultant force (in this case the weight of the object). Question 3 Many candidates were confused between Archimedes' principle and the principle of flotation. This is the second exam in a row where this has been an issue. Lower performing candidates could make real improvements to their grade by learning laws, principles and definitions. 3 of 6

4 Most candidates were able to state that the distance decreased but were less able to communicate a reason to support this statement. Candidates need to realise that marks are awarded for clear points that relate to the underlying physics and include appropriate use of technical language. Question 4 The fact that the candidates had 5 pieces of data to choose from confused all but the most able. Most were able to determine the journey used 6.3 litres of petrol but were unsure of how to proceed from there. Many treated the kwh as a power rather than an energy and subsequently multiplied by ½ hour rather than recognising that it needed to be converted into joules. Part 4(b), albeit with an e.c.f from part (a), was more successful but again the majority of candidates were unable to calculate the average power. Question 5 In part (a) the majority of candidates were able to calculate the area but quite a few only obtained one mark. Many candidates do not set out their workings in a convincing manner in "show that" questions and as a result lose marks. 5(b) proved challenging with many candidates failing to take into account that the area had to equal 66m. Most started their straight line at (3,0) but incorrectly finished it at (14,6). Question 6 Most candidates were able to perform the calculation in 6b(i). Where mistakes occurred these were often for careless transcription of the formula with ½ or rho missing. A significant number of candidates had difficulty in rearranging this formula to make v the subject. Answers to part (c) generally were restricted to more power available to larger WTGs with only the best candidates able to consider the implications on the power per square metre of land. Question 7 The definition in part (a) was not well known. Generally candidates' responses were limited to statements about how good an insulator or conductor the material was. 7b(i) was well answered with most candidates obtaining 1 mark. Fewer were able to communicate effectively why this indicated that the internal temperature was 18 C. The calculations in 7b(ii) and 7b(iii) proved a good discriminator with most candidates making good headway in 7b(ii) and less than half able to complete 7b(iii). Many candidates divided the answer to b(ii) by AΔθ instead of firstly calculating the rate of heat loss through the glass. Question 8 Just over ½ of all candidates were able to perform this calculation correctly. The majority attempted to use the potential divider formula but were either confused by R 1 and R 2 or failed to convert 4.6 kω to 4600 Ω. About ¼ of candidates scored no marks and were unable to make any headway in the calculation at all. 4 of 6

5 In part (b) a surprisingly large number of candidates could not recall that an ntc thermistor's resistance decreases as temperature increases. Question 9 The calculation in part (a) caused problems with many candidates applying the equations of motion for constant acceleration. This was penalised because the acceleration of the snowboarder will vary on this slope. Candidates had to approach this calculation using conservation of energy to gain any marks. Although part (b) was a projectile question the context caused many candidates problems. Just under 40% were able to calculate the vertical component correctly. Many attempted to resolve the velocity at point B using the angle of the slope. Others used 17 ms -1 as the initial vertical velocity. In part (b)(ii) the majority of candidates were able to apply Pythagoras' theorem. A significant number of candidates attempted to use 25 in a velocity triangle and divided their answer to (b) (i) by Sin 25. Part (c) was well answered by the higher achieving candidates. Most other candidates opted for 27 Sin37 or 27 Cos37 showing little appreciation for what they were being asked to calculate. A few candidates attempted to find the vertical component of 27 ms -1 and then find the perpendicular component of this vertical component. Unfortunately they failed to appreciate that the horizontal component of 27ms -1 would also have a component perpendicular to the slope. In part (d) many candidates had difficulty in effectively communicating the main points in this question. They often limited their response to less force and bending of the knees without explaining the physics behind these statements. Others stated that the velocity was higher when landing on a horizontal surface than when landing on a sloped surface. There was not much awareness of the force being related to the rate of change in momentum or rate of change in velocity. Of those candidates who began to discuss force and momentum they often were unable to develop their answers, neglecting to support their explanations with appropriate physics principles or equations. Only the best candidates were able to communicate that the snowboarder experienced a smaller change in momentum/velocity when landing on the slope. Question 10 Less than 20% of candidates were able to draw an appropriate circuit diagram. There were fundamental errors seen in part (a) with lots of confusion between ammeters and voltmeters in series and parallel. Many candidates did not include any method for obtaining a range of current and voltage measurements. 10(b) was another example where lack of exam preparation was evident. Many lower performing candidates could define electromotive force. A significant number of candidates described it as a force or confused energy with power. Typically Grade A candidates were able to produce a high quality definition of emf. Part (c) stretched the candidates with less than 20% gaining 4 marks. In fact a significant proportion of candidates achieved no marks in this part. Of those who made some progress their answers involved reading off of current and voltage and substituting into R=V/I, but no further creditworthy work was present. Again higher achieving candidates produced clear and convincing working. Many other candidates had lots of working that was hard to follow and only served to demonstrate their lack of understanding of the topic. Some candidates lost marks through careless reading of points from the graph in Figure 12; reading I max as 2.4A was common. 5 of 6

6 There was very little insight into the underlying physics in part (d)(i). Candidates seemed to guess at either series or parallel with neither able to give a creditworthy reason for their choice. The majority were not sure of the properties of the graph in Figure 13 that indicated the parallel arrangement of the cells. Part (d)(ii) - The first mark was relatively easy to obtain whereas the second mark was only available to candidates who could clearly demonstrate an understanding of the situation. Many candidates were not specific enough about where the voltage or resistance was different. They failed to use appropriate technical language to support their explanation. Mark Ranges and Award of Grades Grade boundaries and cumulative percentage grades are available on the Results Statistics page of the AQA Website. Converting Marks into UMS marks Convert raw marks into Uniform Mark Scale (UMS) marks by using the link below. UMS conversion calculator 6 of 6

A-LEVEL PHYSICS A. PHA6T Investigative and Practical Skills in A2 Physics (ISA) Report on the Examination June Version: 0.

A-LEVEL PHYSICS A. PHA6T Investigative and Practical Skills in A2 Physics (ISA) Report on the Examination June Version: 0. A-LEVEL PHYSICS A PHA6T Investigative and Practical Skills in A2 Physics (ISA) Report on the Examination 2450 June 2014 Version: 0.1 Further copies of this Report are available from aqa.org.uk Copyright