1.8 Magnetism and electromagnetism

I declare: solidlikelyshaky

1. Explain what a current does in a coil and what a moving magnet does in a coil (the two directions of electromagnetism).
2. Drive a relay from a microcontroller with a transistor and flyback diode, and say why each is there.
3. Take apart a brushed DC motor, name its parts and explain commutation.
4. Measure the starting current of a brushed motor and explain why it exceeds the rated current.
5. State Lenz’s law, show induction with a magnet and a coil on the oscilloscope, and say that the transformer, the motor and the generator are the same thing seen three times.
6. Measure the inductance of a coil and say what the iron core changes.
7. Diagnosis: a brushed motor that runs in fits and starts, brushes, commutator or supply; say how to decide.