PHYS 242 Lecture 25: PHYS242_Lecture_25-27
13 May 2017
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Document Summary
In the late 19th century carl wilhelm r ntgen experimented with cathode ray tubes. Figure 37 shows a sketch of such a tube. Figure 37: a cathode ray tube is a glass vacuum tube with a heated wire (cathode) opposite to an anode plate. If the wire is hot enough and a voltage (typically. 10-100 v) is applied, so called cathode rays" can be observed, which carry an electrical current. Today we know that these cathode rays are electrons. In such a tube, cathode rays are emitted from a hot wire if a voltage is applied across the tube (today we know that these cathode rays are electrons). In 1895 r ntgen found that a new type of radiation is emitted where the cathode rays hit the glass or the anode. It exposes photographic films and causes fluorescence even if the tube is covered. The radiation is not deflected by electric or magnetic fields.
