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Making Things Move with Electricity
📖 Making Things Move with Electricity
Every electric motor — from tiny fans to massive train engines — works on the same principle discovered by Michael Faraday in 1821. When an electric current flows through a wire in a magnetic field, the wire experiences a force. Arrange this cleverly with a coil that can spin, and you get rotation. This simple idea powers electric cars, washing machines, hard drives, and billions of other devices — the motor effect is arguably the most useful discovery in the history of physics!
Inside a DC motor — click each component to see how it works and why the coil spins.
- 1Permanent magnets —
- 2Rotating coil —
- 3Split-ring commutator —
- 4Motor effect force —
Figure 1: Inside a DC motor — click each component to see how it works and why the coil spins.
The Motor Effect
When a current-carrying conductor is placed in a magnetic field, it experiences a force. This happens because the conductor's own magnetic field (from the current) interacts with the external field.
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🧠 Memory Aid
Fleming's Left-Hand Rule: "FBI" — Force (thumb), B-field (first finger), I-current (second finger). Hold your left hand with all three at right angles to each other.
Left hand vs Right hand:
- Left hand = motor effect (force on conductor). Remember: Left = Load bearing / Lifting things (motors lift and move)
- Right hand grip rule = field direction around a wire
DC Motor components — CMBS:
- Coil (carries current)
- Magnets (provide field)
- Brushes (connect supply)
- Split-ring commutator (reverses current)
Now try it yourself
Quiz · Question 1 of 19
What is the motor effect?
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This topic in real past papers
Every real exam question we've found on the motor effect, with a full worked answer.