2016 Physics. Advanced Higher. Finalised Marking Instructions

Transcription

1 National Qualifications Physics Advanced Higher Finalised ing Instructions Scottish Qualifications Authority 06 The information in this publication may be reproduced to support SQA qualifications only on a non-commercial basis. If it is to be used for any other purposes written permission must be obtained from SQA s NQ Assessment team. Where the publication includes materials from sources other than SQA (secondary copyright), this material should only be reproduced for the purposes of examination or assessment. If it needs to be reproduced for any other purpose it is the centre s responsibility to obtain the necessary copyright clearance. SQA s NQ Assessment team may be able to direct you to the secondary sources. These ing Instructions have been prepared by Examination Teams for use by SQA Appointed ers when marking External Course Assessments. This publication must not be reproduced for commercial or trade purposes.

2 General ing Principles for Advanced Higher Physics This information is provided to help you understand the general principles you must apply when marking candidate responses to questions in the paper. These principles must be read in conjunction with the detailed marking instructions, which identify the key features required in candidate responses. (a) (b) (c) (d) (e) (f) (g) (h) (i) (j) (k) (l) s for each candidate response must always be assigned in line with these General ing Principles and the Detailed ing Instructions for this assessment. ing should always be positive. This means that, for each candidate response, marks are accumulated for the demonstration of relevant skills, knowledge and understanding: they are not deducted from a maximum on the basis of errors or omissions. If a specific candidate response does not seem to be covered by either the principles or detailed ing Instructions, and you are uncertain how to assess it, you must seek guidance from your Team Leader. There are no half marks awarded. Where a wrong answer to part of a question is carried forward and the wrong answer is then used correctly in the following part, the candidate should be given credit for the subsequent part or follow on. Unless a numerical question specifically requires evidence of working to be shown, full marks should be awarded for a correct final answer (including units if required) on its own Credit should be given where a diagram or sketch conveys correctly the response required by the question. It will usually require clear and correct labels (or the use of standard symbols). s are provided for knowledge of relevant relationships alone, but when a candidate writes down several relationships and does not select the correct one to continue with, for example by substituting values, no mark can be awarded. s should be awarded for non-standard symbols where the symbols are defined and the relationship is correct, or where the substitution shows that the relationship used is correct. This must be clear and unambiguous. Where a triangle type relationship is written down and then not used or used incorrectly, then any mark for a relationship should not be awarded. Significant figures Data in question is given to 3 significant figures. Correct final answer is 8 6 J Final answer 8 J or 8 58 J or J Award the final mark. Final answer 8 J or J Do not award the final mark Candidates should not be credited for a final answer that includes: three or more figures too many or two or more figures too few, ie accept two more or one fewer The incorrect spelling of technical terms should usually be ignored and candidates should be awarded the relevant mark, provided that answers can be interpreted and understood without any doubt as to the meaning. Where there is ambiguity, the mark should not be awarded. Two specific examples of this would be when the candidate uses a term that might be interpreted as reflection, refraction or diffraction (eg defraction ) or one that might be interpreted as either fission or fusion (eg fussion ). Page 0

3 (m) s are awarded only for a valid response to the question asked. For example, in response to questions that ask candidates to: describe, they must provide a statement or structure of characteristics and/or features; determine or calculate, they must determine a number from given facts, figures or information; estimate, they must determine an approximate value for something; explain, they must relate cause and effect and/or make relationships between things clear; identify, name, give, or state, they need only name or present in brief form; justify, they must give reasons to support their suggestions or conclusions, eg this might be by identifying an appropriate relationship and the effect of changing variables; predict, they must suggest what may happen based on available information; show that, they must use physics [and mathematics] to prove something eg a given value all steps, including the stated answer, must be shown; suggest, they must apply their knowledge and understanding of physics to a new situation. A number of responses are acceptable: marks will be awarded for any suggestions that are supported by knowledge and understanding of physics; use your knowledge of physics or aspect of physics to comment on, they must apply their skills, knowledge and understanding to respond appropriately to the problem/situation presented (for example by making a statement of principle(s) involved and/or a relationship or equation, and applying these to respond to the problem/situation). They will be rewarded for the breadth and/or depth of their conceptual understanding. Page 03

4 (n) ing in calculations Question: The current in a resistor is 5 amperes when the potential difference across it is 7 5 volts. Calculate the resistance of the resistor. (3 marks) Candidate answer + Comment. V = IR mark: formula 7 5 = 5R mark: substitution R = 5 0 Ω mark: correct answer. 5 0 Ω 3 marks: correct answer marks: unit missing Ω 0 marks: no evidence, wrong answer 5. Ω 0 marks: no working or final answer 6. V 75 R 40 I 5 marks: arithmetic error V 7. R 40 mark: formula only I V 8. R mark: formula only I V 75 R I 5 V 75 R 40 I 5 V 5 R 50 I 75 V 75 R 50 I 5 I 75 R 50 V 5 marks: formula & subs, no final answer marks: formula & subs, wrong answer mark: formula but wrong substitution mark: formula but wrong substitution 0 marks: wrong formula 4. V=IR marks: formula & subs, arithmetic error 7 5 = 5 R R = 0 Ω 5. V=IR I 5 R 0 V 75 mark: formula correct but wrong rearrangement of symbols Page 04

5 Detailed ing Instructions for each question Question Answer Max. (a) v 035 t + 6t dv a 035 t 6 dt a (035 50) 6 a 5 3 m s 3 Accept m s m s, 5 30 m s, (b) v 035 t + 6t s v. dt 0045t 063t 0 0 s 3 ( ) ( ) s 94 m 3 Accept 90 m, 93 6 m, m Constant of integration method acceptable. Page 05

6 . (a) (i) velocity changing or changing direction or an unbalanced force is acting or a centripetal/central/radial force is acting (ii) towards the centre towards the axis/pole (b) (i) (A) SHOW QUESTION d OR dt t rad s v d and v r t rad s If final answer not stated, max mark (B) F mr (C) F F 035 N W mg W T 035 (005998) T 068 N mark for calculating weight mark for Pythagorean relationship mark for final answer 3 Accept 0 3, 0 347, mv F r F 048 F 035 N 3 Accept 0 7, 0 676, W mg W tan sin T T 068 N for both (ii) In a straight line at a tangent to the circle Any parabolic path is not acceptable. Page 06

7 3. (a) v v= v v GM r (m s ) 4 (lander returns to surface as) lander v less than escape velocity of comet (b) (i) ( F W) g SHOW QUESTION GMm for both eqns, mg r for equating GM g r g= 3 0 g 40 N kg 4 3 Show question, if final line is missing then a maximum of two marks. If the nd line is missing then mark maximum for F g = W F GM = m r or GM g = r As a starting point, zero marks (ii) Height will be greater Because a reduces with height 3 Must justify question Alternative: Assumption that a is constant is invalid The value for a is too large Page 07

8 4. (a) L b 4 r 3 Accept 3, 304, L L = W (b) 4 L 4r T T Or consistent with (a) Accept 500, 546, T = 550 K (c) That the star is a black body (emitter/radiator) OR the star is spherical/constant radius OR the surface temperature of the star is constant/uniform OR no energy absorbed between star and Earth 5. (a) (i) Frames of reference that are accelerating (with respect to an inertial frame) (ii) It is impossible to tell the difference between the effects of gravity and acceleration. (b) (i) Any convex upward parabola. (ii) Any straight line. (c) The clock on the surface of the Earth would run more slowly. The (effective) gravitational field for the spacecraft is smaller. Or vice versa. Page 08

9 6. Demonstrates no understanding 0 marks Demonstrates limited understanding marks Demonstrates reasonable understanding marks Demonstrates good understanding 3 marks This is an open-ended question. mark: The student has demonstrated a limited understanding of the physics involved. The student has made some statement(s) which is/are relevant to the situation, showing that at least a little of the physics within the problem is understood. 3 Open-ended question: a variety of physics arguments can be used to answer this question. s are awarded on the basis of whether the answer overall demonstrates no, limited, reasonable or good understanding. marks: The student has demonstrated a reasonable understanding of the physics involved. The student makes some statement(s) which is/are relevant to the situation, showing that the problem is understood. 3 marks: The maximum available mark would be awarded to a student who has demonstrated a good understanding of the physics involved. The student shows a good comprehension of the physics of the situation and has provided a logically correct answer to the question posed. This type of response might include a statement of the principles involved, a relationship or an equation, and the application of these to respond to the problem. This does not mean the answer has to be what might be termed an excellent answer or a complete one. Page 09

10 7. (a) (i) T K = b Tkelvin peak 89x0 88 peak 3 3 Accept, 00, 003 Also accept 0035 Incorrect/no conversion to kelvin zero marks peak m (ii) Infrared Consistent with answer to a(i). (b) (i) (curve) A Peak at shorter wavelength/higher frequency (as Temperature is higher) OR Higher/greater (peak) intensity (as greater energy) (ii) curve (approximately) asymptotic to y-axis and decreasing with increased wavelength Intercept of y-axis zero marks Page 0

11 8. (a) (i) p x the uncertainty in the momentum (in the x-direction.) (b) (i) (ii) The precise position of a particle/ system and its momentum cannot both be known at the same instant. OR If the uncertainty in the location of the particle is reduced, the minimum uncertainty in the momentum of the particle will increase (or vice-versa). OR The precise energy and lifetime of a particle cannot both be known at the same instant. OR If the uncertainty in the energy of the particle is reduced, the minimum uncertainty in the lifetime of the particle will increase (or vice-versa). h p (m) slit width 0 nm used At the same instant/ simultaneously required 4 Confusion of accuracy with precision award zero marks. (ii) xp x h 4π x 650 x π 34 0 min uncertainty = 80 m 3 Accept 8, 8, 8 7 (iii) Electron behaves like a wave Interference 3 Any three of the statements can be awarded mark each. Uncertainty in position is greater than slit separation Electron passes through both slits Page

12 9. (a) SHOW QUESTION v m Bqv sin r for both relationships for equating mv r Bq If the final line is missing then a maximum of mark can be awarded (b) (i) (MeV) ( J) 4 Accept, 99, 988 No conversion to J Max mark Ek mv v v m s Calculation of deuteron mass by adding mass of proton and neutron is incorrect max (ii) mv r Bq Final answer consistent with b(i) B Suspend the significant figure rule and accept 0 B 000 T (iii) r will be less m r q and q increases more than m does or q doubles but m 5 Justification involving an increase in charge without mentioning mass max Page

13 0. (a) (i) displacement is proportional to and in the opposite direction to the acceleration F = -ky or equivalent (ii) SHOW QUESTION y Acost dy Asint dt d y dt d y dt d y dt Acos t y y 0 If final line not shown then max mark can be awarded Award zero marks if: dy Asin t appears dt First mark can only be awarded if both the first and second differentiations are included. (b) (i) 0 T 0 T 0 5 rad s - 3 If final line not shown maximum marks 0 f f 0 5 rads OR 0 t 0 5 rads (ii) v ( ) A - y v 5004 v 0 m s - 3 Accept vmax A Accept 0, 0 08, Page 3

14 (iii) EP m y EP E 003 J P 3 Accept 0 03, EK = mv = 0550 = 0033 J Accept 0 03, 0 033, (c) (i) Any valid method of damping. A practical method must be described. For example, place mass in a more viscous medium, increase the surface area of the mass. (ii) amplitude of harmonic wave reducing. Graph must show positive and negative amplitude. Page 4

15 (a) v f v v 33 m s 4 Accept 330, 330 5, (b) E ka E A A A E A 077 (m) 4 A A acceptable method Accept 0 8, 0 768, Final mark is independent and for: sin π(8 t0 357 x) y 077sin π(8t 0357 x) y 077sin(744 t 4 x) Page 5

16 . (a) (The axes should be arranged) at 90 o to each other (eg horizontal and vertical.) Perpendicular to each other. (b) (c) (d) The filter for each eye will allow light from one projected image to pass through. while blocking the light from the other projector. There will be no change to the brightness. Light from the lamp is unpolarised. (As the student rotates the filter,) the image from one projector will decrease in brightness, while the image from the other projector will increase in brightness. (The two images are almost identical). only one projected image to pass through to each eye OR Light from one projector gets through to one eye. Light from the other projector gets through to the other eye Page 6

17 3 (a) SHOW QUESTION V V Q 4 o r 0 4π V (+)360 V 9 Q V k r V 030 OR V V (+)360 V If either a value for k or ε 0 is not given, then a maximum of mark can be awarded. If the final line is missing then a maximum of mark can be awarded (b) (i) V = -360 (V) Q V 4π o r 360 Q 4π Q 6 0 C 3 Accept, 60, 60 Use of acceptable Accept, 60, 600 Use of ratio method acceptable. Must start with V + V = 0 or equivalent. V = +360V zero marks (ii) Q E 4π o r 0 E 4π E E E 00 (N C to right) π ( N C to right) 8 4 Accept 000, 098 Allow correct answer or consistent with b(i). Total 00 N C ( to right ) (iii) Shape of attractive field, including correct direction Field consistent with (b) (i) Skew in correct position Page 7

18 4. (a) µi o B πr 7 6 4π 0 I B 5 0 π 0 I 5 A 3 Accept 3, 50, 500 (b) (i) ignore calibration (less than /3) %unc = 000 / 0 00 = % (ii) reading 5 0/ 500 % Accept % if calibration not ignored. (Accept %, 06%,.06%) 3 Accept 3%, 50%, 500% total%= (reading% +calibration% ) total % = ( 5 + ) = 5% (iii) total % = ( + 5 )= 0 5% abs u/c= = 0 08 A Accept 0, 0 080, Consistent with b(i) and (ii). (c) Uncertainty in measuring exact distance from wire to position of sensor. Page 8

19 5. (a) (i) gradient gradient A F m 3 Accept 9, 9, 9 If gradient calculated using two points from best fit line, full credit possible. (ii) c c c π0 90 m s Accept 3, 94, 94 Or consistent with (a)(i) (b) Systematic uncertainty specific to capacitance or spacing measurement Systematic uncertainty: Large % uncertainty in smallest values of d Stray capacitance Dip in plates/non uniform plate separation. Insufficient/poor choice of range. Systematic uncertainty on its own 0 marks Page 9

20 6. (a) I mr 5 3 Accept 4, 4 7, 4 70 I I kg m 3 (b) (i) Labelling & scales Plotting best fit line ½ box tolerance applies for plotting 3 If rogue point not ignored, do not award the mark for best fit line, unless incorrect plotting does not expose a rogue point. v /m s - Page 0

21 (ii) gradient = 73 or consistent with candidate s best fit line I gh v mr gh I v mr I I=7 80 kg m 3 3 The gradient should be calculated using points from the candidate s best fit line to access the first mark. h I v g mr I I kg m Page

22 (c) Demonstrates no understanding 0 marks Demonstrates limited understanding marks Demonstrates reasonable understanding marks Demonstrates good understanding 3 marks This is an open-ended question. mark: The student has demonstrated a limited understanding of the physics involved. The student has made some statement(s) which is/are relevant to the situation, showing that at least a little of the physics within the problem is understood. marks: The student has demonstrated a reasonable understanding of the physics involved. The student makes some statement(s) which is/are relevant to the situation, showing that the problem is understood. 3 marks: The maximum available mark would be awarded to a student who has demonstrated a good understanding of the physics involved. The student shows a good comprehension of the physics of the situation and has provided a logically correct answer to the question posed. This type of response might include a statement of the principles involved, a relationship or an equation, and the application of these to respond to the problem. This does not mean the answer has to be what might be termed an excellent answer or a complete one. 3 Open-ended question: a variety of physics arguments can be used to answer this question. s are awarded on the basis of whether the answer overall demonstrates no, limited, reasonable or good understanding. [END OF MARKING INSTRUCTIONS] Page