Faraday effect

Principle

The angle of rotation of the polarization- plane of plane polarised light through a flint glass rod is found to be a linear function of the product of the mean flux-densitiy and the length of the optical medium. The factor of proportionally, called Verdet's constant, is investigated as a function of the wavelength and the optical medium.

Benefits

• Experience that magnetic fields can influence light by changing its polarization properties
• Learn how wavelength and the optical medium influence the effect of the magnetic field
• Discover a bridge between the fields of optics and electromagnetism

Tasks

1. To determine the magnetic flux-densitiy between the pole pieces using the axial Hall probe of the teslameter for different coil currents. The mean flux-density is calculated by numerical integration and the ratio maximum flux-density over mean flux-density established.
2. To measure the maximum flux- density as a function of the coil current and to establish the relationship between mean flux-density and coil current anticipating that the ratio found under 1. remains constant.
3. To determine the angle of rotation as a function of the mean fluxdensity using different colour filters. To calculate the corresponding Verdet's constant in each case.
4. To evaluate Verdet's constant as a function of the wavelength.

Learning objectives

• Electromagnetic field interaction
• Electron oscillation
• Electromagnetism
• Polarization
• Verdet's constant
• Hall effect