ConceptConceptDocsDocuments

CAIE IGCSE Physics 4.5.5 The d.c. motor Question Bank

Practise linking coil forces, turning effect, commutators and motor design changes in diagrams of simple d.c. motors.

Syllabus
2026–2028
Course
Physics 0625

Exam points

  • predict motor turning effect changes from current, magnet strength, resistance or coil turns
  • explain how the split-ring commutator reverses current every half-turn to keep rotation one way
  • use force arrows on opposite coil sides to determine rotation direction and zero moment positions

Covered syllabus points

4.5.5.1—A current-carrying coil in a magnetic4.5.5.2—Operation of an electric motor

4.5.5 The d.c. motor question 1

[Maximum number: 3]

Fig. 9.1 shows a simple direct current (d.c.) electric motor. The coil rotates about the axis when there is a current in the coil. The coil is connected to the rest of the circuit by the brushes.

Fig. 9.1

Fig. 9.1

Question (a)

(a)

State any difference each of the following changes makes to the rotation of the coil in Fig. 9.1:

[ 3 ]

Question (i)

(i)

changing the polarity of the power supply to that shown in Fig. 9.2

Fig. 9.2

Fig. 9.2

[ 1 ]

Question (ii)

(ii)

changing the coil to the new coil shown in Fig. 9.3

Fig. 9.3

Fig. 9.3

[ 1 ]

Question (iii)

(iii)

using a stronger magnetic field.
[Total: 8]

[ 1 ]
All question bank results loaded