Ei-8 Magnetic deflection of Beta Rays


To demonstrate that beta particles are charged particles electrons and that they may be deflected by a magnetic field


  • Geiger tube
  • Sr90 source
  • Retort stand
  • Paper
  • Aluminium foil
  • Lead blocks

Magnetic Deflection of Beta Rays


A strontium 90 source is placed below the poles of a strong horseshoe magnet. A lead aperture is used to ensure that beta particles are reasonably well collimated. With no magnet the detector produces maximum counts when in line with the source. Introducing the magnet requires the detector to be perpendicular to the source illustrating the deflection has been quite dramatic.