Spark image

Cathode Ray Deflection Tube

The electron gun shoots a beam of electrons across the tube. The downwards electrostatic force on an electron can be balanced by an upwards force due to the magnetic field produced by the Helmholtz coils. The upper slider controls the magnetic field while the lower slider controls the electric field.

Switch on the electron gun by pressing the Start button.

© Keith Gibbs/John Bourne 2013