GCE Physics B (Advancing Physics) H157/01: Foundations of physics Advanced Subsidiary GCE Mark Scheme for November 2020

GCE Physics B (Advancing Physics) H157/01: Foundations of physics Advanced Subsidiary GCE Mark Scheme for November 2020 Oxford Cambridge and RSA Examinations GCE Physics B (Advancing Physics) H157/01: Foundatio ...

GCE Physics B (Advancing Physics) H157/01: Foundations of physics Advanced Subsidiary GCE Mark Scheme for November 2020 Oxford Cambridge and RSA Examinations GCE Physics B (Advancing Physics) H157/01: Foundations of physics Advanced Subsidiary GCE Mark Scheme for November 2020Oxford Cambridge and RSA Examinations OCR (Oxford Cambridge and RSA) is a leading UK awarding body, providing a wide range of qualifications to meet the needs of candidates of all ages and abilities. OCR qualifications include AS/A Levels, Diplomas, GCSEs, Cambridge Nationals, Cambridge Technicals, Functional Skills, Key Skills, Entry Level qualifications, NVQs and vocational qualifications in areas such as IT, business, languages, teaching/training, administration and secretarial skills. It is also responsible for developing new specifications to meet national requirements and the needs of students and teachers. OCR is a not-for-profit organisation; any surplus made is invested back into the establishment to help towards the development of qualifications and support, which keep pace with the changing needs of today’s society. This mark scheme is published as an aid to teachers and students, to indicate the requirements of the examination. It shows the basis on which marks were awarded by examiners. It does not indicate the details of the discussions which took place at an examiners’ meeting before marking commenced. All examiners are instructed that alternative correct answers and unexpected approaches in candidates’ scripts must be given marks that fairly reflect the relevant knowledge and skills demonstrated. Mark schemes should be read in conjunction with the published question papers and the report on the examination. © OCR 2020H157/01 Mark scheme November 2020 2 Annotations Annotation Meaning Benefit of doubt given Contradiction Incorrect response Error carried forward Benefit of doubt not given Power of 10 error Omission mark Technical error (includes rounding & arithmetic errors) Error in number of significant figures Correct response X Incorrect response Wrong physics or equation Indicates level of response in extended response questions indicated * by the question number TE L1 L2 L3H157/01 Mark scheme November 2020 4 Abbreviations, annotations and conventions used in the detailed Mark Scheme (to include abbreviations and subject-specific conventions). Annotation Meaning / alternative and acceptable answers for the same marking point (1) Separates marking points reject Answers which are not worthy of credit not Answers which are not worthy of credit IGNORE Statements which are irrelevant ALLOW Answers that can be accepted ( ) Words which are not essential to gain credit __ Underlined words must be present in answer to score a mark ecf Error carried forward AW Alternative wording ORA Or reverse argumentH157/01 Mark scheme November 2020 5 MARKING INSTRUCTIONS Section A: MCQs Question Answer Marks Guidance 1 C 1 2 A 1 3 B 1 4 C 1 5 C 1 6 D 1 7 A 1 8 D 1 9 B 1 10 B 1 11 B 1 12 B 1 13 B 1 14 A 1 15 C 1 16 B 1 17 C 1 18 A 1 19 D 1 20 D 1 Total 20H157/01 Mark scheme November 2020 6 SECTION B Question Expected Answer Mark Rationale/Additional Guidance 21 a (b = log2256) = 8  1 Bare answer scores mark b 457 x 353 / 1024  = 158 (kilobytes)  1 1 Method Evaluation. ALLOW 161 kB (using 1000B = 1kB) Total 3 Question Expected Answer Mark Rationale/Additional Guidance 22 a C B A  2 Answers in the order shown 2 marks if all three correct ALLOW 1 mark for one correct b i A  1 b ii A  1 Total 4H157/01 Mark scheme November 2020 7 Question Expected Answer Mark Rationale/Additional Guidance 23 a (P = VI) = 12 x 2.4  = 28.8  W  1 1 1 ALLOW 29 ALLOW Js-1 but no other alternatives b t = 2 x 60 = 120 (s)  (E = V2t/R ) = 122 x 120 / 4  = 4320 (J)  1 1 1 Conversion to seconds anywhere seen in solution ALLOW other equivalent e.g. E=VIt if correct ALLOW 72 (J) for 2 marks c Energy dissipated/lost to surroundings  so less energy goes to heating the block  1 1 DO NOT ALLOW just “energy lost” Total 8 Question Expected Answer Mark Rationale/Additional Guidance 24 a Light dependent resistor  1 ALLOW LDR b (V1/V2 = R1/R2) = 2/6 = R/18 000  R = 6000 (Ω)  1 1 Valid method and correct substitution. ALLOW alternative methods e.g. potential divider equation and substitution. ALLOW one mark for calculation of current in circuit (3.3 x 10-4 A as part method) c Adjust lighting to the required level (on/off point)  Adjust variable resistor until reading on V is 6.0V  1 1 ALLOW until light just turns on Total Total Section B 5 20H157/01 Mark scheme November 2020 8 SECTION C Question Expected Answer Mark Rationale/Additional Guidance 25 a Distance travelled = 2 mm AND Time taken = 800ms (Speed = 2/800 ) = 0.0025 (ms-1)  1 1 Identification of both values Evaluation b The ball is accelerating  1s (1000 ms) is less than halfway between n = 2 and n = 3  1 1 Second mark for some idea that the instantaneous speed varies between n = 2 and n = 3 but that at 1s it is closer to the n = 2 frame c The distance travelled between frames is constant  And remains constant for all subsequent frames  1 1 Second mark must be clear that the distance travelled is constant for every frame past n = 5 d ( 3 x 10-3 / 0.8) = 0.00375 (ms-1 )  uses all four frames to get values (e.g. 9 x 10-3 / 2.4)  1 1 ALLOW statement that as the distance between all four frames is the same then (3 x 10-3 / 0.8) is valid. Total 8H157/01 Mark scheme November 2020 9 Question Expected Answer Mark Rationale/Additional Guidance 26 a No variation (in brightness)  1 ALLOW stays the same brightness b Decreases to zero  Then increases (rapidly)  1 1 c 56  1 Only this value d (Completely plane) polarised  Perpendicular (to the axis of the polarising filter)  1 1 ALLOW horizontally e (±) 1 degree  1 Insist on unit f (Yes) – a curve with minimum at 58  Would pass through all the error bars  1 1 REJECT ‘the point at 58 has an error bar that touches zero’ Total 9H157/01 Mark scheme November 2020 10 Question Expected Answer Mark Rationale/Additional Guidance 27 a 2.05  1 Check in table and on answer space b i Points at (5.00, 2.05) and (5.83,2.40)  Line of best fit drawn  1 1 ECF from part a. ALLOW ½ square tolerance on plotting b ii Values read or triangle marked where ∆x > 1.5 x 1014  = 4.3 x 10-15 (Vs)  1 1 Method mark for large range being used. ALLOW max ½ square misread ALLOW ecf from ½ square misreads only c E (= 2.40 x 1.60 x 10-19) = 3.84 x 10-19 (J)  1 3sf answer only. d 1 Vs = 1.6 x 10-19 (Js)  h = gradient x 1.6 x 10-19  = 6.9 (6.856) x 10-34 (Js)  1 1 1 Must use gradient in calculation, or zero marks. e They may not be identical  This improves accuracy/precision  1 1 ALLOW check the one in use wasn’t somehow anomalous ALLOW find an average p.d.H157/01 Mark scheme November 2020 11 f Any one pair from: Darken the room / shield the LED / view through black paper tube  To improve contrast  To go from unlit to lit and back again to find turn on point Sometimes get flickering at turn-on point Any suggestion to get finer control of p.d. e.g. to use potential divider Because the LVU control is too coarse 1 1 1 for suggestion 1 for explanation ALLOW any other reasonable pairs of suggestion / explanation Total Total Section C Total Sections B & C 13 30 50OCR (Oxford Cambridge and RSA Examinations) The Triangle Building Shaftesbury Road Cambridge CB2 8EA