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The cathode ray particles originates in a discharge tube from the
(A) Cathode
(B) Anode
(C) Source of high voltage
(D) Residual gas

Last updated date: 13th Jun 2024
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Hint The cathode is the negative electrode and the anode the positive electrode. Cathode rays are negatively charged particles. So we need to analyse the structure of the discharge tube to find where the particles originate.

Complete step by step answer
In general, cathode rays are negatively charged particles observed in evacuated discharged tubes containing two electrodes. It occurs when a voltage is applied across the two electrodes. One of these electrodes is connected to the negative terminal of the voltage source, and another to the positive terminal. Hence, the electrode connected to the negative terminal called the cathode is negative while the electrode connected to the positive terminal called anode is positive. In various experiments, it was observed that when this potential difference is applied a glow is noticed at the glass behind the anode, hence it was concluded that some ray travels from the cathode to the anode, hence the name cathode rays. In older versions, below a certain voltage, these cathode rays are not observed, this is because sufficient electric fields have to be created to detach the atoms from the cathode. This electric field actually ionizes the residual gases in the tube to become positive by stripping off electrons. These ions get attracted towards the cathode, colliding with the cathode and further releasing electrons.
There are discharge tubes which use the thermionic effect, which is the removal of electrons from the surface of a metal when it is heated. The cathode is heated and thus releases electrons into the space near itself, but since the cathode is negatively charged, these electrons are repelled, accelerating towards the anode.
From these, we can conclude that the cathode rays originate from the cathode.
So the correct answer is option A.

The principle of the discharged tube even till date is, in application, used to create fluorescent lamps, neon lamps, and similar lighting equipment. Also, the same principle is used in a cathode ray tube which is utilized in old-fashioned televisions.