School of Physics Lecture Demonstration Manual

Ef-1 The Maltese Cross

Published: Tuesday 14 March 2006 - Updated: Tuesday 29 March 2011


To demonstrate that

 a) cathode rays are emitted from the cathode and travel in straight lines and

 b) cathode rays will not penetrate a thin sheet of metal.



Click on pictures to enlarge.

Maltese Cross Pic

Maltese Cross Diagram


The apparatus consists of an evacuated tube containing a tiltable metal shield in the shape of a cross. The electron beam produces a shadow of the cross on the glass.

Safety notes

Electrical safety 

Sharps safety 


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