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:

1. Electrically - using the electric field of the built-in plate capacitor
2. 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.

Technical Specifications:

• Maximum filament voltage: =7.5V AC/DC
• Maximum anode voltage: 5 kV
• Maximum capacitor voltage: 500 V
• Typical Operation at 4000V: Anode current: 1.8mA, Beam current: 4µA

Requires the following products to operate:

• B8A49463 - Universal Stand
• B8R02653 - EHT Power Supply - to power the anode
• B8R07149 - EHT Experiment Leads (3 required)
• B8G85458 - Bench Power Supply - to power the filament
• B8R06545 - 4mm Leads
• B8A49475 - Helmholtz Coils
• B8G85483 - College Power Supply Unit - to power the Helmholtz Coils