GCSE Physics Electromagnetism Generator and Motor Effect Notes

What happens in a motor effect?
- A current passes though the coil.
- This produces a magnetic field.
- The magnetic field interacts with the magnetic field from the
permanent magnet.
- This causes a force to be exerted on the coil.
- Therefore, the coil rotates.
- The split ring commutator reverses the current every half turn to
keep the coil spinning in the same direction.


What happens in the generator effect?
- The coil is moved in a magnetic field from a permanent magnet.
- Therefore, the coil experiences a changing magnetic field.
- The coil ‘cuts’ the field lines
- This induces a potential difference across the coil.
- If there is a complete circuit a current is induced


How does a microphone work? (generator
effect)
- Sound waves enter and vibrate the diaphragm at the same
frequency as the sound waves.
- The diaphragm moves the coil.
- The coil experiences a changing magnetic field.
- The coil ‘cuts’ the field lines of the permanent magnet
- This induces a potential difference across the coil.
- If there is a complete circuit a current will be induced


How does a speaker work? (motor effect)
- A current pass through the coil
- This creates a magnetic field.
- This field interacts with the magnetic field of the permanent
magnet.
- This causes a force to be exerted on the coil.
- The signal is alternating and changes direction, this changes the
direction of the magnetic field and therefore the force.
- This changing force vibrates the core therefore producing sound.