Anode Rays (Canal Rays) | Experiment, Procedure

Definition of Anode Rays

anode rays

The streams of positively charged particles are called anode rays or positive rays, or canal rays.

Discovery of Anode Rays

Anode rays (or Canal rays) were observed in experiments by a German scientist, Eugen Goldstein, in 1886. Goldstein used a gas discharge tube that had a perforated cathode.

A “ray” is produced in the holes (canals) in the cathode and travels in a direction opposite to the “cathode rays,” which are streams of electrons. Goldstein called these positive rays “Kanalstrahlen” – canal rays because it looks like they are passing through a canal.

In 1907 a study of how this “ray” was deflected in a magnetic field revealed that the particles making up the ray were not all the same mass. The lightest, formed when a little hydrogen was in the tube, was calculated to be 1837 times as massive as an electron.

  He discovered that positively charged rays were emitted from the anode in the discharge tube. The experiment conducted by him is commonly referred to as the canal ray experiment. These rays were called canal rays.

Goldstein conducted his discharge tube experiments and named Kathodenstrahlen, or cathode rays, the light emissions examined by others.

Canal Ray Experiment

canal ray experiment

Canal Ray experiment is the experiment performed by German scientist Eugen Goldsteinin 1886 that led to the discovery of the proton.

The discovery of proton, which happened after the discovery of the electron, further strengthened the structure of the atom. In the experiment, Goldstein applied high voltage across a discharge tube that had a perforated cathode. A faint luminous ray was seen extending from the holes in the back of the cathode.

Apparatus of the Experiment

apparatus of the experiment

The apparatus of the experiment incorporates the same apparatus as the cathode ray experiment, which is made up of a tube made of glass containing two pieces of metal ions at the different ends, which acts as an electrode. The two metal pieces are connected with an external voltage. The pressure of the gas inside the tube is lowered by evacuating the air.

Anode Ray Tube

anode ray tube

Goldstein used a gas-discharge tube that had a perforated cathode. When an electrical potential of several thousand volts is applied between the cathode and anode, faint luminous “rays” are seen extending from the holes in the back of the cathode.

These rays are beams of particles moving opposite the “cathode rays,” which are streams of electrons that move toward the anode. Goldstein called these positive rays “channel rays” or “canal rays” because they were produced by the holes or channels in the cathode.

Procedure of the Experiment

procedure of the experiment

The procedure of the anode rays experiment is;

1. Apparatus as set up by providing a high voltage source and evacuating the air to maintain low pressure inside the tube.

2. High voltage is passed to the two metal pieces to ionize the air and make it a conductor of electricity.

3. The electricity starts flowing as the circuit was complete.

4. 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.

5. These rays were moving in the opposite direction of cathode rays and were named canal rays.

Properties of Anode Rays

Here are some properties of anode rays:

1. Anode rays travel in a straight line.

2. These rays are deflected by electric and magnetic fields to show that these rays are positively charged particles. For example, these rays are attracted towards the negative plate in the electric field, which means rays are positively charged particles.

3. These rays consist of material particles and rotate the paddle wheel placed in their path.

4. Anode rays produce a heating effect when struck against a metal foil.

5. The charge to mass (e/m) ratio for positive rays is considerably smaller than that for electrons and is not constant but depends on the nature of the gas taken in the discharge tube. In other words, the value of e/m for a positive ion depends upon the charge of the ion and its mass.

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