Grade 12 Physical Sciences · Electricity and Magnetism · Paper 1 (Physics)

Electrodynamics Grade 12

Real Electrodynamics past paper questions and answers from 2023 to 2025, with each memo split into the ticks examiners give. Try one, mark yourself, and see exactly which skill cost you marks.

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Question 1.9 · November 2025 · Paper 1 · National (DBE) · 2 marks

Various options are provided as possible answers to the following questions. Each question has only ONE correct answer. Choose the answer and write only the letter (A–D) next to the question numbers (1.1 to 1.10) in the ANSWER BOOK, e.g. 1.11 E.

1.9 How does the commutator in a DC motor ensure that the coil rotates continuously in ONE direction?(2)

A By reducing friction
B By converting AC to DC
C By reversing the direction of the current in the coil
D By maintaining electrical contact between the external and the internal circuits

Work it out on paper first. Then mark yourself with the official memo, one tick at a time.

Electrodynamics skills

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More Electrodynamics Grade 12 questions and answers

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4. Question 8.3.1 · November 2025 · Paper 1 · National (DBE) · 3 marks
Two identical headlights, $L_{1}$ and $L_{2}$ , and a starter motor, M, of a car are connected to a battery, as shown in the circuit diagram below. The resistance of each headlight is $12 Ω$ , while the resistance of the starter motor is $0, 1 Ω$ . The emf ( $ε$ ) and internal resistance (r) of the battery are unknown.

The ammeters and the connecting wires have negligible resistance, while the voltmeter has a high resistance. Switches $S_{1}$ and $S_{2}$ are initially open.
8.3 Switch $S_{1}$ is now closed and switch $S_{2}$ is opened. The power dissipated by each headlight is $15$ W.

Answer the questions that follow.
8.3.1 Calculate the current passing through $L_{1}$ .(3)
Show the memo (3 ticks)Memo
1. ✓
  METHOD 1: Formula $P = I^{2} R$
  1 mark · Calculate electrical power and energy
2. ✓
  METHOD 1: Substitution $15 = I^{2} (12)$
  1 mark · Calculate electrical power and energy
3. ✓
  METHOD 1: Answer with unit $I = 1, 12$ A
  1 mark · Calculate electrical power and energy
5. Question 9.1.3 · May/June 2025 · Paper 1 · National (DBE) · 3 marks
9.1 The diagram below represents a simplified version of an AC generator.

The induced current flows from X to Y in the coil when the coil is rotated clockwise, as shown in the diagram below.

Answer the questions that follow.
9.1.3 Sketch a graph of induced current versus time for ONE complete rotation of the coil from the horizontal position, as shown in the diagram above.(3)
Show the memo (3 ticks)Memo
1. ✓
  Starts at maximum currentThe AC graph starts with maximum current (positive or negative maximum) at $t = 0$ .
  1 mark · Describe generators and motors
2. ✓
  One complete cycleThe graph is drawn for one cycle / one complete wavelength.
  1 mark · Describe generators and motors
3. ✓
  Correct shapeCorrect shape: a cosine graph.
  1 mark · Describe generators and motors
6. Question 8.2.1 · November 2024 · Paper 1 · National (DBE) · 3 marks
$L_{1}$ and $L_{2}$ are two light bulbs that have the following ratings:

$L_{1}$ : $36$ W ; $20$ V and $L_{2}$ : $48$ W ; $32$ V

The two bulbs are connected as shown in the circuit diagram below. The battery has an internal resistance of $0, 6 Ω$ while the conducting wires and the ammeters have negligible resistance. $R_{1}$ and $R_{2}$ are resistors.
8.2 If both light bulbs operate as RATED, calculate the:
8.2.1 Reading on ammeter $A_{2}$ (3)
Show the memo (3 ticks)Memo
1. ✓
  Formula $P = V I$
  1 mark · Calculate electrical power and energy
2. ✓
  Substitution $48 = 32 I$
  1 mark · Calculate electrical power and energy
3. ✓
  Answer $I = 1, 5$ A
  1 mark · Calculate electrical power and energy
7. Question 1.9 · May/June 2024 · Paper 1 · National (DBE) · 2 marks
Various options are provided as possible answers to the following questions. Each question has only ONE correct answer. Choose the answer and write only the letter (A–D) next to the question numbers (1.1 to 1.10).
1.9 A simplified diagram of an electrical machine is shown below.

What type of machine is this?(2)
1. A A DC motor
2. B An AC motor
3. C A DC generator
4. D An AC generator
Show the memo (1 tick)Memo
1. ✓
  Choose the correct optionThe coil is connected to a BATTERY, so electrical energy is supplied to the coil: it is a motor, not a generator.
  
  The coil is connected through a split-ring commutator (not two separate slip rings), which keeps the coil turning in one direction with a DC supply: a DC motor.
  
  Answer: A
  2 marks · Describe generators and motors
8. Question 8.3 · May/June 2024 · Paper 1 · National (DBE) · 4 marks
A battery of emf $12$ V and internal resistance $0, 2 Ω$ is connected to three resistors, a high-resistance voltmeter and two switches, an ammeter and connecting wires of negligible resistance, as shown in the circuit diagram below. The three resistors have different and unknown resistances.

The resistance of $R_{Y}$ is TWICE the resistance of $R_{X}$ .

When both switches are CLOSED, the reading on the ammeter is $5, 5$ A.
8.3 Calculate the power dissipated by resistor $R_{X}$ .(4)
Show the memo (4 ticks)Memo
1. ✓
  OPTION 1: Current in $R_{X}$ $I_{X} = \frac{2}{3} (5, 5) = 3, 67$ A
  
  OR $I_{X} = \frac{R _{//}}{R _{X}} I_{t o t a l} = \frac{1 , 98}{2 , 97} (5, 5) = 3, 67$ A
  1 mark · Use series and parallel circuit rules
2. ✓
  OPTION 1: Formula $P = I^{2} R$
  1 mark · Calculate electrical power and energy
3. ✓
  OPTION 1: Substitution $P = (3, 67)^{2} (2, 97)$
  1 mark · Calculate electrical power and energy
4. ✓
  OPTION 1: Answer with unit $P = 40$ W
  1 mark · Calculate electrical power and energy
9. Question 1.9 · November 2023 · Paper 1 · National (DBE) · 2 marks
Various options are provided as possible answers to the following questions. Each question has only ONE correct answer.
1.9 A split-ring commutator connects the coil of a generator to an external circuit.

Which ONE of the combinations below is CORRECT for the magnitude and direction of the induced current in the external circuit?(2)
1. A Magnitude: Constant; Direction: Constant
2. B Magnitude: Constant; Direction: Changes
3. C Magnitude: Changes; Direction: Constant
4. D Magnitude: Changes; Direction: Changes
Show the memo (1 tick)Memo
1. ✓
  Correct optionA split-ring commutator makes a DC generator. The commutator reverses the connections every half turn, so the current in the external circuit always flows in the same direction, but its size still rises and falls as the coil turns.
  
  Answer: C
  2 marks · Describe generators and motors
10. Question 8.2.3 · November 2023 · Paper 1 · National (DBE) · 4 marks
The circuit diagram below shows a battery with an emf of $12$ V and an internal resistance of $0, 5 Ω$ connected to three resistors, a light bulb, a switch, an ammeter and connecting wires. The ammeter and connecting wires have negligible resistance.
8.2 Switch S is initially CLOSED.

Calculate the:
8.2.3 Power dissipated by resistor R $_{3}$ (4)
Show the memo (4 ticks)Memo
1. ✓
  FormulaCurrent in R $_{3}$ : the two parallel branches each have $15 Ω$ , so the current splits equally:
  $1, 5 = 2 I_{R 3}$ , $I = 0, 75$ A
  
  $P = I^{2} R$
  1 mark · Calculate electrical power and energy
2. ✓
  Substitution of the correct current for R3 $= (0, 75)^{2}$
  1 mark · Use series and parallel circuit rules
3. ✓
  Substitution of R3 $\times 15$
  1 mark · Calculate electrical power and energy
4. ✓
  Answer with unit $P = 8, 44$ W
  1 mark · Calculate electrical power and energy

Electrodynamics Grade 12 videos

Short lessons from South African teachers first. Videos load only when you tap play, to save your data.

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