4.Main Content
experiments
A magnet moving near a coil on a C-core
Class experiment
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
- Galvanometer, sensitive to e.g. 3.5𢠥.5 mA, 10 ohm resistance
Safety
Read our standard health & safety guidance
Procedure
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.
Teaching notes
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