6.
Corpuscles
In his experiment, J.J.
Thomson had found a charged particle that had a specific
charge two thousand times greater than that of the hydrogen
ion, the lightest particle known in 1897. Once the charge
on the particles was measured he could say with certainty
that they were two thousand times lighter than hydrogen.
This
explained how they could pass through thin sheets of
gold. Particles this small could pass between atoms
in a solid.
J.J.
used aluminium to make most of his electrodes. He
repeated his experiments using cathodes made from different
metals, including iron and platinum, and found that
the specific charge did not change. He argued that
the cathode ray consisted of small charged particles,
and by using different types of cathodes realised that
the particles existed in many types of atoms. He concluded
that the particles, which he called 'corpuscles', were
a universal constituent of matter - they form part of
all the atoms in the universe. We now know these particles
as electrons.
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