Product Overview
This classic experiment uses a “Magic Eye Tube” — once popular in early radios for tuning — to visualize the path of an electron beam and demonstrate the effects of a magnetic field. The tube is now used to study electron deflection and determine the mass of an electron through the interaction between electric and magnetic fields.
The tube is mounted on a plastic base with a valve socket and terminals for connecting to a power supply. When the heater and anode are powered, electrons flow from the central cathode to a surrounding circular anode, illuminating a fan-shaped green glow on a fluorescent screen. Introducing a magnetic field bends the path of the beam, visibly curving the fan shape.
In this experiment, an Air Core Solenoid (sold separately) is placed around the tube so the electron beam lies at the solenoid’s center. By varying current and using the known number of solenoid turns, the field strength can be calculated. The observed beam curvature allows calculation of the electron’s mass using fundamental physical laws.
Connections to Electron Tube Unit:
• Heater: 12 V AC or DC, 2 A
• Anode to Cathode: Up to 250 V DC, 10 mA (filtered)
Air Core Solenoid (sold separately)
• Maximum current: 10 A
• Typical current for experiment: 2 A
• Number of turns: approx. 710
Suggested Power Supplies:
• For anode/cathode and solenoid circuits: AC/DC Digital Discharge Tube Power Supply
• For heater terminals: Regulated AC/DC 0–12V, 2A Power Supply
Apparatus Dimensions:
82 × 115 × 105 mm; 3.2 × 4.5 × 4.1 in
Weight: 0.13 kg; 0.29 lb
Note: The Air Core Solenoid must be ordered separately.
Instruction Sheet: Download PDF
Designed and manufactured in Australia.
