Permeability and permittivity of air

Item Code: SK201

Principle and Working:

Repulsive forces between two current carrying conductors, which is very small, is measured using a very sensitive balance technique based on a diode laser, scale and fractional weights to form an optical lever. This measurement is used to calculate permeability of air.
Similarly small attractive forces between two charged capacitor plates is measured. This measurement is used to calculate the permittivity of air. An indirect estimate of the speed of light can be made from the experimental values of permeability and permittivity which verifies the relationship.




  • DC Regulated power supply with safety sockets and dual temperature controlled exhaust fan.
  • High voltage supply with safety socket and smart thermal safety switch.
  • Highly sensitive balance for permeability and permittivity experiment.
  • Diode Laser with 0.8 mW power.

  • To measure the force between current carrying conductor and determine the permeability of air.
  • To measure the force of attraction between charged capacitor plates and determine the permittivity of air.
  • To verify the relationship of speed of light with permeability and permittivity of air.
  • Coulomb & current Balance : Dimension 30 x 35.5cm, Levelling knobs. 4mm safety socket, Lever position 25.5cm, Al, straight conductor L=33.5cm, dia.=3mm, Al (U type), Straight conductor L=26.5cm, dia.=3mm, Max. current 20A, Al Parallel plate 12.5cmx12.5cmx0.8mm (LxWxT) Max. current 20 Amp.
  • Power Supply : 0-30V DC, 0-20A, Input voltage 220V, ±5%, 50Hz AC, Voltage resolution 0.1V, Display 2½ digit LED, Current Resolution 0.1 Amp,Primary fuse 8 Amp.
  • HV Power Supply : 220V, ± 5%, 50Hz AC, 0-600V DC, Voltage Resolution 10V, Voltage Display Analog. Short Circuit Current 100μ A.
  • 1 Coulomb and current balance kit
  • 1 Power supply 0-30V DC, 0-20A
  • 1 Power supply 0-600V, 10mA
  • 1 Weight box
  • 2 Cylindrical base
  • 1 Wooden scale (100 cm)
  • 1 Resistance module
  • 1 Flexible plug leads (50 cm), yellow
  • 1 Flexible plug leads (100 cm), red & black
  • 1 Measuring tape (3 metre)
  • Permittivity of air
  • Null Method
  • Electrostatic force
  • current balance
  • Coulomb law
  • Parallel plate
  • Capacitor
  • Permeability
  • Speed of light
  • Magnetic field
  • Force between current carrying wires.