Objective: Demonstrate the straight-line propagation of electrons in the absence of any field
Straight-line propagation of electrons in the absence of a field can be demonstrated in a Maltese-cross
tube by showing how the shadow of the electron beam coincides with the shadow due to a light beam.
Any deviation from the straight-line propagation of the beam, due to a magnetic field for example, can
be seen since the shadow is then caused to move.