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🔌 Electric Motors and the Motor Effect

Find out how a wire carrying current in a magnetic field feels a force, and how that motor effect spins the motors all around you.

3
lessons
~15 min
to learn
🔬 Science
subject
Teens
level
Start the course →

What you’ll learn

  1. The Motor EffectExplain the motor effect: a current-carrying wire in a magnetic field feels a force, and predict its direction.The motor effect is the force experienced by a current-carrying wire placed in a magnetic field, caused by the wire's own field interacting with the magnets' field. The force acts at right angles to both, and Fleming's left-hand rule predicts its direction, with the First finger for Field, seCond finger for Current, and thuMb for Motion.
  2. Building a MotorDescribe the parts of a simple DC motor and the role of the split-ring commutator.A simple DC motor has a coil of wire between two magnets connected to a battery, and the motor effect pushes one side up and the other down so the coil turns. Reversing the current or field reverses the force, and a split-ring commutator swaps the current every half turn to keep the coil spinning continuously.
  3. Motors EverywhereRecognise everyday uses of motors and describe how to make a motor spin more powerfully.Electric motors drive washing machines, drills, fans, electric cars, and phone vibrations, each using a current-carrying coil pushed inside a magnetic field. A motor spins more powerfully if you increase the current, add more turns to the coil, or use stronger magnets, all of which boost the motor-effect force.

Questions this course answers

What is the motor effect?

The motor effect is the force felt by a current-carrying wire placed in a magnetic field.

In Fleming's left-hand rule, what does the thumb represent?

The thuMb shows the Motion (force), the First finger the Field, and the seCond finger the Current.

What happens to the force if you reverse the direction of the current?

Reversing the current reverses the direction of the force on the wire.

What job does the split-ring commutator do in a motor?

The commutator reverses the current every half turn so the force keeps the coil rotating the same way.

A simple DC motor is mainly made from a coil of wire placed between...

A coil of wire sits between two magnets; the current makes it feel the motor effect and spin.

Which change would make a motor spin more powerfully?

A bigger current increases the motor-effect force, giving a more powerful spin.

Grounded in trusted sources

  • BBC Bitesize
  • The Physics Classroom
  • Britannica

Every Wunder lesson is built from real, reputable sources — never invented.

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