The perrin tube may be used to show that charge can be accumulated in the fara day pail incorporated, that the charge does not disappear when the filament is switched off and therefore the cathode rays must consist of charged particles. Electron defection senstivity may be measured using helmholtz coils to defalt the beam. Cathode ray tube operation may also be demonstrated, using a secondry coil for transvers field.Contains a diode electron gun with filament and cylendrical anode in the nack of the tube, and 45° to the axis. The end of the sphere has internal phosphor coating.
Maximum filament voltage     7.5V
Anode voltage                        2000 to 5000
Typical operation                   At 4000V, anode current 1.8mA beam current 4mA