AQA AS Level Physics Paper 2 2020 Mark Scheme.

AQA AS Level Physics Paper 2 2020 Mark Scheme. Question Answers Additional Comments/Guidance Mark AO details 01.1 Max one from: internal ray is a radius (of the block) OR internal ray travels along a normal OR ray meets (glass-air) boundary at 90 OR angle of incidence is zero (so angle of emergence/refraction is zero) 1 2.1c 01.2 Straight line ruled from centre of protractor through ABC Takes a pair of readings: 24 or 66; and angle consistent with their line Use of Snell’s Law with their angles 1.48 or 1.52 for 1 line must be reasonable and must pass through intersection of the cross-wires and must not pass above the centre of A or below the centre of B Must be between 0° and 90° Must be a positive value to 3 sf. 4 3.2b 2.1h 2.1h 2.1h 01.3 1.47 or 1.471 Reject 1.5 or 4 sf; ignore any unit written 1 3.1a S - The Marketplace for Revision Notes & Study Guides Downloaded by: jameshoulton | Distribution of this document is illegal S - The Marketplace for Revision Notes & Study Guides MARK SCHEME – AS PHYSICS – 7407/2 – JUNE 2020 7 01.4 0.08 (mm) Only acceptable answer 1 3.1a Question Answers Additional Comments/Guidance Mark AO details 01.5 Calculates one percentage uncertainty OR Calculates max or min value Adds their percentage uncertainties OR attempt to use percentage n = 0.5(max− min) 1.47 × 100 1.4(%)  For 1 allow ecf from 01.4; expected answers are % uncertainty in (R2 – R0) = 0.08 100 0.56(0)% 14.28  = % uncertainty in (R2 – R1) = 0.08 100 0.82(4)% 9.71  = min 14.28 0.08 1.45(0); 9.71 0.08 n − = = + max 14.28 0.08 1.49(1); 9.71 0.08 n + = = − Ecf for 2 from wrong percentage uncertainties or wrong max or min values Condone 3 or 4 sf 3 3.1b 3.1b 3.1b Total 10 S - The Marketplace for Revision Notes & Study Guides Downloaded by: jameshoulton | Distribution of this document is illegal S - The Marketplace for Revision Notes & Study Guides MARK SCHEME – AS PHYSICS – 7407/2 – JUNE 2020 8 Question Answers Additional Comments/Guidance Mark AO details 02.1 to limit (maximum) current (when variable resistor is set to zero) to prevent overheating (of cell) OR to prevent damage to cell OR otherwise cell would discharge quickly Accept ‘so cell is not short-circuited’ for 1 ‘to avoid damaging components’ is not enough for 2 2 3.2b 3.2b 02.2 Line ruled through bottom of second error bar and top of ninth (3rd from right) error bar Determines their gradient, with x ≥ 0.2 (A) (–)1.0 ± 0.1 (/ V A–1 ) Ignore unit if given. Allow tolerance of 2 mm inside either error bar. Expect to see 2 sf in any answer 3 3.1a 2.1h 2.1h 02.3 Attempt to calculate mean of their Gmin and –1.3 1.1 () Allow positive G values Ecf from 02.2. 1 mark max if r given as negative 2 3.1a 3.1a S - The Marketplace for Revision Notes & Study Guides Downloaded by: jameshoulton | Distribution of this document is illegal S - The Marketplace for Revision Notes & Study Guides MARK SCHEME – AS PHYSICS – 7407/2 – JUNE 2020 9 02.4 States that = V + Ir OR calculates R = 0.39 () Use of = V + Ir OR = I(R + r) 1.4 (V) Allow ruled line drawn through (0.94, 0.37) and (0.70, 0.65) Adds their gradient to read off at I = 1.0 A OR Use of y=mx+c with their gradient Intercept (c) determined Ecf from 02.3. 3 sf max 3 2.1h 2.1h 2.1h Total 10