Question

A strong argument for particle nature of cathode rays is that they

• A. Produce fluorescence
• B. Travel through vacuum
• C. Get deflected by electric and magnetic fields
• D. Cast shadows

Answer 1

The correct option is A Produce fluorescence

Since the electrons have a negative charge, they are repelled by the cathode and attracted to the anode. They travel in straight lines through the empty tube. The voltage applied between the electrodes accelerates these low mass particles to high velocities. Cathode rays are invisible, but their presence was first detected in early vacuum tubes when they struck the glass wall of the tube, exciting the atoms of the glass and causing them to emit light, a glow called fluorescence.

So, the answer is option (A).