PHYSICS | Atomic Physics and Radiation | SubSection+ A
A. Electron Diffraction Tube
The tube uses an electron gun with an indirectly heated cathode to project a narrow converging beam of electrons through a thin layer of graphiticised carbon supported on a fine mesh grid over the exit aperture of the gun. The cathode rays are diffracted in passing through the carbon layer and produce a ring pattern on the phosphor coated end of the tube. Study of the ring pattern and its variation with different anode voltages permits the study and verification of the de Broglie hypothesis, shows the dual nature of the electron, permits the calculation of the spacing of diffracting planes and suggests the probable arrangement of carbon atoms. Use with the Universal Stand.
• Filament voltage: 7.5V a.c./d.c. • Anode voltage: 2000 to 5000V d.c. • Anode current: typical 0.15mA at 4000V d.c. Supplied complete with instructions. Direct Delivery – up to 5 weeks E8A49566
B. Deflection e/m Tube
For determining e/m by balanced electrostatic deflections or by magnetic deflection using the Helmholtz coils.
Simple electrostatic and magnetic deflection may be demonstrated and the relationships shown between the plate potentials or coil currents and the degree of deflection. The ‘electron mirror’ effect producing trochodial spirals is easily shown and also the magnetic focusing at points along the trochoid.
The tube is the standard glass sphere with cylindrical neck and has a diode electron gun with filament and cylindrical anode. In the centre of the sphere and angled at 15° across the axis is a mica screen 90mm long x 60mm high approximately. The undivided side is coated with phosphor and produces a clear fluorescent trace when irradiated by the electron beam. The top and bottom edges of the mica plate are supported by horizontal metal plates which are connected to 4mm plugs in the side caps and provide the electrostatic deflection field when connected to an E.H.T. supply. Use with the Universal Stand.
• Maximum filament voltage: 7.5V • Anode voltage: 1000 to 5000V d.c. • Typical operation: 2000 to 4500V • Anode current: 0.1mA approx. at 4000V Supplied complete with instructions. Direct Delivery – up to 6 weeks E8A49530
C. Experiment Lead, Safety Plug and Socket
Safety lead for use with EHT and HT power supplies ending in a 4mm safety-plug.