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Sir William Crookes' 1885 investigations revealed that heated cathodes in a vacuum produced 'Cathode rays,' radiation capable of making gases glow and substances emit light. By the mid-nineties, these rays were known to carry a negative charge and be deflected by magnetic fields, leading to debate over their nature as waves or particles. In 1897, J. J. Thomson, using a discharge tube experiment with high-voltage electricity through low-pressure gas, demonstrated these streams were indeed particles, which he named electrons. A typical discharge tube is a long glass tube with two sealed metal electrodes.

Production of Cathode Rays:
In 1885, Sir William Crookes carried out a series of
investigations into the behavior of metals heated in a vacuum.
The experiment of Crookes and others showed that a heated
cathode produced a stream of radiation, which could cause
gases at low pressure to glow and which made other
substances emit light. The radiation emitted from the cathode
was given the name 'Cathode rays'. By mid-nineties it was
known that these rays could be deflected by a magnetic field
and they carried a negative charge. Some scientists felt that
these rays were waves and others were inclined to think they
were particles.
In 1897, J. J. Thomson showed that the stream of
radiation were indeed particles called electrons. He conducted
the famous discharge tube experiment, by passing electricity
at high voltage through a gas at low pressure. A common
discharge tube is a long glass tube having two metal plates,
sealed at its two ends as electrodes. It has a side tube through