A slinky is used as a variable density solenoid while a magnetic field probe is used to investigate the field in the coil. A value for the permeability of free space is determined.


  • Understand the nature of a magnetic field around a solenoid.
  • Relate magnetic field to current, length and number of turns of a solenoid.
  • Perform calculations with the formula.
  • Measure the earth's magnetic field and direction.
  • Links to Stage 6 Physics Syllabus Content:
  • PH11-11/Magnetism.
  • Use magnetic field lines to model qualitatively the direction and strength of magnetic fields produced by magnets, current-carrying wires and solenoids and relate these fields to their effect on magnetic materials that are placed within them. (ACSPH083)
  • Conduct investigations into and describe quantitatively the magnetic fields produced by wires and solenoids, including: (ACSPH106, ACSPH107)
  • Investigate and explain the process by which ferromagnetic materials become magnetised. (ACSPH083)
  • Apply models to represent qualitatively and describe quantitatively the features of magnetic fields.