Welcome to practical physicsPracticle physics - practical activities designed for use in the classroom with 11 to 19 year olds
 

A magnet moving near a coil on a C-core

Class practical

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. 3.5–0–3.5 mA, 10 ohm resistance

Health & Safety and Technical notes


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. 
 
Apparatus set-upd 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