Question

Which statement(s) about cathode rays is/are correct?

• A. They travel in straight lines towards cathode.
• B. They produce fluorescent discharge through the walls of the tube.
• C. They produce heating effect.
• D. They can effect photographic plate.

Answer 1

Answer: (B), (C), (D)

Properties of Cathode rays
(1)They travel in straight lines away from cathode with very high velocity ranging from ${10}^{7}to{10}^9$ m/sec.
(2)A shadow of metallic object placed in the path is cast on the wall opposite to the cathode.
(3)They produce a green glow when strick the glass wall matter. Light is emitted when they strike the zinc-sulphide screen.
(4)When a small pin wheel 10.0 is placed in their path, the blades of the wheel are set in motion. Thus the cathode rays consist of material particles which have mass and velocity.
(5)They are deflected by the electric and magnetic fields. When the rays are passed between two electrically charged plates, these are deflected towards the positively charged plate. It shows that cathode rays carry -ve charge. These particles carrying negative charge were called negatrons by Thomson.
(6)They produce heat energy when they collide with the matter. It shows that cathode rays posses Kinetic energy which is converted into heat energy when stopped by matter.
(7)These rays affect the photographic plate.