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Topic 10 Practice Paper: Electricity and circuits — mark scheme

QuizQuipPractice Series
QQ/IGCSE-PHYS/T10

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

Mark scheme

Electricity and circuits

Topic 10 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]

QuestionAnswer and marking pointsMarks
Total for Question 11
Total for Question 21
Total for Question 31
Total for Question 41
Total for Question 51
Total for Question 61
Total for Question 71
Total for Question 81
Total for Question 91
Total for Question 101

Section B: Structured questions[20 marks]

QuestionAnswer and marking pointsMarks
11(a)

R = V/I = 6.0 ÷ 0.30 = 20 Ω.

  • use of R = V/I [1]
  • 20 Ω [1]
2
11(b)

It doubles (to 40 Ω): for a metal conductor the resistance is directly proportional to its length, because the electrons must pass twice as many lattice ions.

  • doubles [1]
  • R ∝ length explained [1]
2
11(c)

I = V/R = 6.0 ÷ 40 = 0.15 A.

  • use of I = V/R [1]
  • 0.15 A [1]
2
Total for Question 116
12(a)

I = P/V = 36 ÷ 12 = 3.0 A.

  • use of P = IV [1]
  • 3.0 A [1]
2
12(b)

E = Pt = 36 × 20 = 720 J (or E = IVt = 12 × 3.0 × 20 = 720 J).

  • E = IVt or Pt used [1]
  • 720 J [1]
2
12(c)

Mostly transferred to the internal (thermal) energy of the surroundings as heat and light radiation from the lamp.

  • thermal energy of surroundings / light [1]
1
Total for Question 125
13(a)

I = P/V = 2300 ÷ 230 = 10 A.

  • use of I = P/V [1]
  • 10 A [1]
2
13(b)

13 A: the smallest rating above the 10 A working current — safe in normal use but quick to melt on a fault. A 3 A fuse would blow at once; a 30 A fuse would allow damaging currents.

  • 13 A chosen [1]
  • just above working current justified [1]
2
13(c)

Water conducts, so damp skin lowers the resistance of the path through the body, allowing a dangerous current to flow to earth.

  • damp skin conducts / lower resistance path [1]
1
Total for Question 135
14(a)

9.0 − 6.0 = 3.0 V, because series p.d.s add to the source value.

  • 3.0 V [1]
1
14(b)

I = V₁/R₁ = 6.0 ÷ 10 = 0.60 A.

  • use of I = V/R [1]
  • 0.60 A [1]
2
14(c)

R₂ = V₂/I = 3.0 ÷ 0.60 = 5.0 Ω. [1]

1
Total for Question 144

— End of mark scheme —