A strong argument in favour of the particle nature of cathode rays is that they

Options

A. produce fluorescence
B. travel through vacuum
C. can rotate a light paddle wheel placed in their path
D. cast shadow of the objects lying in their path

Answer

**Step-by-Step Solution:**

1. **Understanding Cathode Rays**: Cathode rays are streams of electrons observed in vacuum tubes. They are produced when a high voltage is applied across electrodes in a vacuum.

2. **Observation of Deflection**: When cathode rays pass through electric and magnetic fields, they exhibit deflection. This means that their path changes when subjected to these fields.

3. **Effect of Electric Field**: When an electric field is applied, cathode rays (which are negatively charged particles) are attracted towards the positive plate and repelled by the negative plate. This behavior is characteristic of particles with charge.

4. **Effect of Magnetic Field**: Similarly, when a magnetic field is applied, the moving cathode rays experience a force (Lorentz force) that causes them to curve in a direction perpendicular to both the velocity of the rays and the magnetic field. This again indicates that they behave like particles.

5. **Conclusion**: The deflection of cathode rays by both electric and magnetic fields strongly supports the argument that they are particles, specifically electrons, rather than waves.

**Final Argument**: The ability of cathode rays to be deflected by electric and magnetic fields is a strong argument in favor of their particle nature, as only charged particles exhibit such behavior.

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