Question

When J.J Thomson placed a light paddle wheel inside the tube in the path of the cathode rays, the wheel started rotating. This led him to conclude that cathode rays are particulate in nature.

how can we say that cathode rays are particulate in nature.?

Answer 1

The movement of paddle wheel by interaction of cathode rays indicates that it has momentum which is transferred from cathode ray to paddle wheel after collision. The cathode ray has momentum also indicates that it must carry some mass. Any thing which carries mass does not considered as wave but it considered as particles. That is why the rotation of paddle wheel by interaction of cathode ray proves the particle nature of cathode rays.