NHHS 2025 PHY PRELIM P3 MS

2025 Phy Prelim Practical P3_NHHS_suggested marking scheme Question suggested answer marks 1 (a) (i) L, W and H recorded to 1 dp and correct units sample data : 12.5 cm x 6.6 cm x 2.0 cm (blocks differ) 1 (ii) Base on (ai) correct working, significant figures and units Volume = 12.5 x 6.6 x 2.0 = 165 cm3 = 170 cm3 (if 2 sf) Density = 416/170 = 2.5 g/cm3 (2 sf) {actual density of glass block is about 2.2 to 2.8 g/cm³} 1 1 (b) (i) i recorded to the nearest degree 40 o 1 (ii) Recorded to the nearest degree with the correct units (eg. θ = 101o) Recorded to the nearest 0.1 cm with the correct units (eg. x = 1.0 cm) 1 1 (c) Points P3 and P4 marked as far away as possible Ensure the block is placed accurately on the given rectangle Ensure light source with slit is placed close to the glass block. 1,1 (d) Difficult to place the incident ray accurately on the line drawn (40°) Difficult to locate the exact centre of the emergent ray to draw the points Ambient light makes it difficult to locate emergent ray. 1,1 Question suggested answer marks 2 (b) (i) d value recorded with unit to nearest 0.1 cm 1 (ii) It is difficult to make ruler vertical It is difficult to access the centre of lamp / filament / judge where the filament is / ruler is too far from lamp 1 (c) (i) Sensible value for VS with 2 dp precision (range from 4.00 V to 4.45 V) 1 (ii) Sensible value for VAB with 2 dp precision (eg VAB = 2.20 V) 1 (iii) 𝐼𝐼 = 𝑉𝑉𝐴𝐴𝐴𝐴 𝑅𝑅 𝐼𝐼 = 2.20 470 = 𝟎𝟎. 𝟎𝟎𝟎𝟎𝟎𝟎𝟎𝟎𝟎𝟎𝟎𝟎 (or 4.7mA) 1 (iv) VL = VS - VAB = 4.35 – 2.20 = 2.15V 𝑅𝑅𝐿𝐿 = 𝑉𝑉𝐿𝐿 𝐼𝐼 𝑅𝑅𝐿𝐿 = 2.15 0.00468 = 𝟎𝟎 𝟒𝟒𝟒𝟒 𝛀𝛀 (3 sf) 1

(c) Marking points • constant variables: (need 2) • surrounding light intensity • value Vs constant • R = 470 Ω • Brightness of bulb 1 • description of procedures: • d as independent variable and record VAB • calculate I and calculate VL • to calculate RL (dependent variable) 1 • vary d to get at least 5 sets of RL • plot a suitable graph: Plot RL against d 1 1 • Υ is ½ of the gradient of the graph 1 Question suggested answer marks 3 (a) Any two from: - Weights placed on the base of each retort stand - Bosses are attached as low as possible - d is not too large / the spring is not too stretched - The orientation of the base of the retort stands (facing away) 1,1 (b) (i) 38.0 cm ± 4.0 cm 1 (ii) Correct calculation of L2 / 100 using candidate’s value with unit and appropriate sf correct calculation unit & sf 1 (c) (i) • Measure time for 10 oscillations and divide this by 10 • Wait for oscillations to stabilise before starting the timing • Count oscillations as the rod moves at its fastest in the same directions (through