Canal Ray Experiment
Canal Ray experiment is the experiment performed by German scientist Eugen Goldsteinin 1886 that led to the discovery of proton. The discovery of proton which happened after the discovery of electron further strengthened the structure of atom. In the experiment, Goldsteinapplied high voltage across a discharge tube which had a perforated cathode. A faint luminous ray was seen extending from the holes in the back of the cathode.
Apparatus of the experiment
The apparatus of the experiment incorporates same apparatus as of cathode ray experiment which is made up of a tube made of glass containing two pieces of metals at the different end which acts as electrode. The two metal pieces are connected with external voltage. The pressure of gas inside the tube is lowered by evacuating the air.
Procedure of the experiment
- Apparatus is setup by providing a high voltage source and evacuating the air to maintain low pressure inside the tube.
- High voltage is passed to the two metal pieces so as to ionize air and make it conductor of electricity.
- The electricity starts flowing as circuit was complete.
- When the voltage was increased to several thousand volts, a faint luminous ray was seen extending from the holes in the back of the cathode.
- These rays were moving in the opposite direction of cathode rays and was named canal rays.
When very high voltage is applied, it ionizes the gas and it is positive ions of gas that constitutes the canal ray. It is actually the nucleus or kernel of the gas that was used in the tube and hence it has properties different from the cathode rays which were made up of electrons.
- Unlike cathode rays, canal rays depend upon the nature of gas present in tube. It is because, the canal rays are composed of positive ionized ions formed by ionization of gas present in tube.
- The charge to mass ratio for the particles of ray was found to be different for different gases.
- The behavior of particles in electric and magnetic field was opposite to that of cathode rays.
- Some of the positively charged particles carry multiples of fundamental value of charge.
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