A magnet moving near a coil on a C-core
In this experiment the coil of the wire is wound on a soft iron core and a permanent magnet is moved relative to it.
Apparatus and materials
For each student group
Copper wire, insulated with bare ends, 200 cm
C-core, laminated iron
Permanent bar magnet
Health & Safety and Technical notes
a Wind a coil of roughly 20 turns on one arm of a C-core.
b Connect the coil by long leads to a galvanometer.
c Place a magnet across the ends of the core. Observe the effect.
d Remove the magnet. Again observe the effect.
e Find out how the deflection on the galvanometer changes if the core is removed from the coil.
f Investigate the factors which affect the deflection on the galvanometer.
Students will find that:
- there is only a current when the coil and magnet are moving relative to each other;
- faster movement results in a bigger deflection;
- the iron core increases the size of the current;
- the current changes direction when the magnet moves towards and away from the coil.
This experiment was safety-checked in December 2004