Discovery of Protons

How the proton was discovered?

William Crooks experiment on the discharge tube is the landmark for the discovery of the fundamental particles, electron, and proton. The experimental set up as shown in the figure below:

It was said that the cathode rays emits from source  irrespective of shape and size of the cathode. Now the scientist we called Goldstein tried the experiment with perforated aluminum as a cathode.

Perforated aluminium 

The set up was the same as setting up of William Crook with high voltage, low pressure except of the perforated Cathode. When the switch was on: Cathode rays traveled from cathode to anode and spark was noted at the anode, this case was already studied by the scientists but new thing was simultaneously the spark occurred in front of the cathode on the wall of the discharge tube. This observation leads to the discovery of the positive charges of anode rays or canal rays.

Interpretation

As cathode rays emits they knock out the electrons of the gases present inside the tube. After ejection of the electron, the gases molecules becomes positively charged and they are attracted towards the cathode (negatively charged bodies). The positive gas particles are absorbed by the cathode when they strike on the body and those positive charge particles which pass from the hole (body of the anode is perforated) are responsible for the generation of spark on the wall of the discharge tube.  A series of observation was done under the influence of the electric and magnetic field. He studied the nature of Hydrogen ions.

The nature of helium, oxygen, neon ions were observed and concluded that the properties of anode rays depend as the nature of gases taken. It is because hydrogen has one proton; Helium has two, so the nature of anode rays shows variation.

Later on, Rutherford confirmed these anode rays as PROTRONS positively charged particles with the  ‘α’-Particles Gold foil experiment.

(When alpha particles bombarded from the source few particles deflected towards source so this observation concluded the  presence of positive charge particles at the center.)

Also Read how electron was discovered click the link Discovery of Electron