Cathode Rays and the Crookes Tube

The Crookes tube is a cathode ray tube.

Discussion

A Crookes tube, such as the one shown in this movie, is one form of what are called cathode ray tubes, or CRTs. The Crookes tube is a sealed glass tube from which virtually all air has been removed. At the right hand end of the tube shown here is the cathode, or negative electrode; at left hand end is the anode, or positive electrode, which is connected to ground. Between cathode and anode is a phosphor coated metal strip placed at an angle within the Crookes tube. The end of this metal strip that is nearest the cathode is bent so that it forms a barrier between the cathode and that part of the tube to the left of this barrier. The only path for a beam or ray from the cathode to the left of this barrier is through a narrow horizontal slit cut in it.