Explain using a neat diagram conducted by Goldstein in 1886 that led to the discovery of protons.
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Solution
The experimental apparatus is made up of a glass tube containing two pieces of metal ions at the different end which act as an electrode.
These two metal pieces are connected with an external voltage.
By air evacuation the pressure inside the tube is lowered.
When high voltage is passed through the metal pieces, the air inside is ionised and made it a conductor of electricity.
When voltage is increased, a faint luminous ray was seen extending from the wholes in the back of the cathode.
These rays were moving in the opposite direction of cathode rays and were named as canal rays.
He concluded that the behaviour of canal rays as they were also affected by magnetic and electric fields but in an opposite way to that of cathode rays.
Thus the charge of these rays will be positive in nature and were later known to be protons.
