Question

Explain using a neat diagram the experiment conducted by J J Thomson in 1897 that led to the discovery of electrons.

Answer 1

• J J Thomson took a tube made up of glass containing two pieces of metal as an electrode.
• He used a vacuum pump to evacuate gas to reduce their ionisation.
• The air inside the chamber is subjected to high voltage and flowed from the negative electrode to the positive electrode.
• He observed a particle stream ray coming from out of the negatively charged electrode to the positive electrode (anode).
• He concluded that these were the negatively charged particles present inside the atom called electrons.
• These rays are called cathode rays since they are coming from the cathode.
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