Highly evacuated electron tube with focusing electron gun and fluorescent screen inclined relative to the beam axis so that the path of the beam can be seen and the effects of electric and magnetic fields can be studied
The electron beam can be deflected using two methods:Electrically ‐ using the electric field of the built‐in plate capacitor
Magnetically ‐ using external Helmholtz Coils (B8A49529)You are also able to determine the fundamental electron charge‐to‐mass ratio (e/m) and study mean electron velocities using field cancellation
The Perrin Tube may be used to show that charge can be accumulated in the Faraday pail incorporated, that the charge does not disappear when the filament is switched off and therefore that cathode rays must consist of charged particles
Electron deflection sensitivity may be measured using Helmholtz coils to deflect the beam
Cathode ray tube operation may also be demonstrated, using a 'secondary coil' for the transverse field
The Perrin tube comprises a standard spherical glass body with a cylindrical neck containing a diode electron gun with filament and cylindrical anode, and a Faraday's pail in the sphere, at 45� to the axis
Connections to the diode electron gun are via 4mm sockets in the moulded cap and the Faraday's pail connection is via a 4mm plug in 1 of the side caps
The end of the sphere ihas an internal phosphor coating providing a luminescent screen
