Skip to content
Dabour HubLEARN · PRACTICE · EXPLORESign inStudent

6.4.1Chemical Reactions

The Motor Effect — Cambridge IGCSE Chemistry 0620 Revision Notes & Topical Questions

5 min read 4 parts Lesson 12 of 21 Unit quiz

📚 Cambridge IGCSE Chemistry 0620 Hub / Topical Revision
🩺
100% Curriculum Specification Match Lesson Doctor Verified
The only platform with 100% curriculum specification match and verified interactive question banks.
0%read

Part 1 of 4The Motor Effect

6.4.1 The Motor Effect
Motor effect
  • A current-carrying conductor placed in a magnetic field experiences a force, because the two magnetic fields interact.
Field from the wire
  • The current produces its own circular magnetic field around the wire, which combines with the external field.
Stronger force
  • The force is greater when the current is larger, or when the external magnetic field is stronger.
Direction of the force
  • The force is perpendicular to both the current direction and the external magnetic field direction.

Part 2 of 4A Simple DC Motor

1
A current flows through a rectangular coil, which is placed between the poles of a permanent magnet.
2
The motor effect produces opposite forces on the two sides of the coil, so the coil turns.
3
A split-ring commutator reverses the current direction every half turn, so the forces keep turning the coil in the same direction.
4
Increasing the current, using a stronger magnet or adding more turns to the coil increases the turning force.

Part 3 of 4Factors in the Motor

Factors in the Motor
Current
  • A larger current gives a larger force on the conductor and a faster turning coil.
Field strength
  • A stronger magnetic field gives a larger force on the conductor for the same current.
Number of turns
  • More turns of wire on the coil give a bigger total turning force for the same current.
Commutator
  • Without a commutator the coil would only rock back and forth instead of rotating continuously.

Part 4 of 4Exam Checklist & Tips

6.4.1 – Key Points for the Exam

  • Motor effect The force on a current-carrying conductor placed in a magnetic field.
  • Commutator A split-ring that reverses the current in the coil each half turn.
  • Turning force The force that causes the coil of a motor to rotate.
  • Magnetic field A region in which a magnet or current experiences a force.
  • Coil A loop or series of loops of wire, used in motors and generators.

Common Mistakes

  • Saying the magnetic field of a permanent magnet is produced by the current in the coil.
  • Forgetting the commutator, so the coil would only rock back and forth.
  • Claiming the force acts along the wire rather than at right angles to it.
  • Thinking the motor effect creates a current; it is the generator effect that induces current from motion.

Last updated:

\n