T = 1 / 780 OR = 1.28 × 10–3 0.25 × 1.28 × 10–3 = 3.2 × 10–4 (s) Allow correct alternative approach using distance of 0.04m travelled by progressive wave in ¼ cycle divided by speed. 0.04 /125 = 3.2 × 10–4 (s) 3 (c) (i) antinode 1 (ii) 2 x 0.240 = 0.48 m gets 1 mark out of 2 ‘480m’ 2 (iii) (f = v/λ = 124.8 or 125 / 0.48 ) = 260 (Hz) ecf from cii 1 [13] M9. (a) (wave) B (the parts of the) spring oscillate / move back and forth in direction of / parallel to wave travel OR mention of compressions and rarefactions Second mark can only be scored if first mark is scored 2 (b) (i) (double ended arrow / line / brackets) from between two points in phase 1 (ii) wave A: arrow vertically upwards wave B: arrow horizontally to the left 2
T = 1 / 780 OR = 1.28 × 10–3 0.25 × 1.28 × 10–3 = 3.2 × 10–4 (s) Allow correct alternative approach using distance of 0.04m travelled by progressive wave in ¼ cycle divided by speed. 0.04 /125 = 3.2 × 10–4 (s) 3 (c) (i) antinode 1 (ii) 2 x 0.240 = 0.48 m ‘480m’ gets 1 mark out of 2 2 (iii) (f = v/λ = 124.8 or 125 / 0.48 ) = 260 (Hz) ecf from cii 1 [13] M9. (a) (wave) B (the parts of the) spring oscillate / move back and forth in direction of / parallel to wave travel OR mention of compressions and rarefactions Second mark can only be scored if first mark is scored 2 (b) (i) (double ended arrow / line / brackets) from between two points in phase 1 (ii) wave A: arrow vertically upwards wave B: arrow horizontally to the left 2
AS-Waves-and-Optics.docx