Topic 7 Practice Paper: General wave properties and sound — mark scheme (print)

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QQ/IGCSE-PHYS/T7

IGCSE · Cambridge IGCSE Physics (Extended (Core + Supplement))

Mark scheme

General wave properties and sound

Topic 7 Practice Paper · Maximum mark: 30

Notes for markers

Award one mark for each point marked [1], up to the marks shown for the part.
Accept answers worded differently that show the same understanding.
Units are required where the answer line shows one. ecf: allow an error carried forward.

Section A: Multiple-choice questions[10 marks]

Question	Answer and marking points	Marks
	Total for Question 1	1
	Total for Question 2	1
	Total for Question 3	1
	Total for Question 4	1
	Total for Question 5	1
	Total for Question 6	1
	Total for Question 7	1
	Total for Question 8	1
	Total for Question 9	1
	Total for Question 10	1

Section B: Structured questions[20 marks]

Question	Answer and marking points	Marks
11(a)	Transverse: each coil vibrates up and down, at right angles to the direction the wave travels along the spring. transverse [1] coil vibrates at right angles to the spring’s length [1]	2
11(b)	v = fλ = 12 × 0.50 = 6.0 m/s — the same speed as the single pulse. 6.0 m/s [1]	1
11(c)	Energy is carried along, but the matter is not: each coil only oscillates about its own fixed position while the disturbance travels. energy transferred [1] matter not transported / coils oscillate in place [1]	2
11(d)	λ = v/f = 6.0 ÷ 24 = 0.25 m. [1]	1
	Total for Question 11	6
12(a)	λ = 25 mm = 0.025 m; v = fλ = 8.0 × 0.025 = 0.20 m/s. wavelength in metres [1] 0.20 m/s [1]	2
12(b)	They slow down, so their wavelength shortens (λ = 0.12 ÷ 8.0 = 15 mm) and the direction of travel bends — refraction caused by the change of speed. slow down / wavelength shortens to 15 mm [1] direction bends: refraction [1]	2
12(c)	Circular (semicircular) ripples spread out beyond the gap — diffraction, strongest because the gap is narrow. circular spreading beyond the gap [1] diffraction named [1]	2
	Total for Question 12	6
13(a)	The vibrating surface pushes and pulls the air, creating compressions where air is squashed together alternating with rarefactions where it is spread out, travelling outwards. surface vibration pushes/pulls the air [1] compressions and rarefactions formed [1]	2
13(b)	Longitudinal: the air particles vibrate back and forth parallel to the direction the sound travels. longitudinal / parallel vibration [1]	1
13(c)	The sound fades to silence: with no air particles there is nothing to compress and carry the longitudinal vibrations out of the jar. sound fades / silence [1] no medium to transmit the vibrations [1]	2
	Total for Question 13	5
14(a)	Total path = 1450 × 0.20 = 290 m; depth = 290 ÷ 2 = 145 m. [1]	1
14(b)	Total path = 1450 × 0.34 = 493 m; depth = 493 ÷ 2 = 246.5 ≈ 247 m. [1]	1
14(c)	The measured time covers the pulse travelling down to the object and the echo travelling back up, so the one-way depth is half the total path. down-and-back doubling explained [1]	1
	Total for Question 14	3

— End of mark scheme —