Topic 11 Practice Paper: Magnetism and electromagnetic effects — mark scheme (print)

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QQ/IGCSE-PHYS/T11

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

Mark scheme

Magnetism and electromagnetic effects

Topic 11 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
1	CInduced magnetism: the near end becomes S (attracted to the magnet’s N), so the far end is N.	1
2	ASteel retains its magnetism, making permanent magnets; soft iron loses magnetism easily.	1
3	DUnlike poles attract: the lines run directly from the north pole to the south pole through the gap.	1
4	BCloser spacing means a stronger field; the arrows only give direction.	1
5	CInside the solenoid the field is strong, straight and uniform along the axis.	1
6	AThe e.m.f. grows with the rate of cutting field lines — double the speed, double the e.m.f.	1
7	DSlip rings with brushes carry the a.c. output from the spinning coil; the split-ring commutator is the reversing device used in d.c. motors.	1
8	BThe force reverses if either the current or the field is reversed — but not if both are.	1
9	ANs = Np × Vs/Vp = 920 × 12/230 = 48 turns.	1
10	CSame power at higher voltage means smaller current; cable losses vary as I²R, so they shrink drastically.	1

Section B: Structured questions[20 marks]

Question	Answer and marking points	Marks
11(a)	It is also a north pole: like poles repel, so the hanging magnet’s N pole swings away. north pole approaching [1] like poles repel [1]	2
11(b)	The field lines run almost straight across the gap from the N pole to the S pole, bunched tightly together. lines from N to S across the gap [1] bunched / strong between them [1]	2
11(c)	The direction of the force on a north pole placed at that point — from N towards S. force on a north pole / N to S [1]	1
	Total for Question 11	5
12(a)	Concentric circles centred on the wire, in planes perpendicular to it. circles around the wire [1]	1
12(b)	The field is stronger, so the needle aligns more firmly (snaps round more strongly) in the same directions; the pattern of directions is unchanged. field stronger [1] needle aligns more strongly, same directions [1]	2
12(c)	It returns to pointing along the Earth’s own magnetic field (north–south), because the wire’s field has vanished. aligns with Earth’s field / north–south [1] wire’s field gone [1]	2
12(d)	An electromagnet (used in scrapyard cranes, relays, bells or magnetic locks). electromagnet named [1]	1
	Total for Question 12	6
13(a)	The coil’s sides cut across the magnetic field lines as they rotate, and motion across field lines induces an e.m.f. sides cut field lines [1] cutting/motion induces e.m.f. [1]	2
13(b)	A smooth wave (sine-like) alternating positive and negative, with two complete cycles — one per revolution — passing through zero twice each revolution. alternating wave shape [1] two cycles for two revolutions [1]	2
13(c)	Cycles arrive twice as often (double the frequency) and the peaks reach twice the e.m.f. higher frequency and larger peaks [1]	1
	Total for Question 13	5
14(a)	Vs = Vp × Ns/Np = 230 × 50/1000 = 11.5 V. use of Vp/Vs = Np/Ns [1] 11.5 V [1]	2
14(b)	Ip = VsIs/Vp = (11.5 × 4.0) ÷ 230 = 0.20 A. IpVp = IsVs used [1] 0.20 A [1]	2
	Total for Question 14	4

— End of mark scheme —