The Properties of ANODE Rays

1. They consist of Positively charged particles. Their mass is virtually the same as that of the atoms from which they are derived and is found to be equal to the atomic mass of the gas in the discharge tube.
2. They Travel in straight lines: They cast a shadow of the objects placed in their way.
3. They are capable of producing physical and chemical changes.
4. They Produce mechanical effect: A paddle wheel placed in their path starts rotating.
5. They can penetrate thin metal foils.
6. They can produce ionization in gases.
7. Rays are positively charged: Anode rays are deflected towards the negative plate of an electric field.
8. They are deflected by electrical and magnetic fields just as the cathode rays but in opposite directions showing that they are oppositely charged, i.e., they carry positive charge. Since their deflection is very little, they consist of very heavy particles.
9. The nature of the anode rays depends upon the gas taken in the discharge tube. Different gases give different types of positive rays, which contain particles having different masses and different charges. Therefore the e/m ratio is not constant for positive ray particles obtained from different gases.

In the case of hydrogen the e/m ratio is the highest as the positive particles obtained from hydrogen are the lightest. The positive particles obtained from hydrogen gas are called 'protons'. It comes from the Greek word 'Proteios' meaning 'of first importance'.

Formation of positive rays

When high electrical voltage is applied to a gas, its atoms break up into negatively charged particles (electrons) and positively charged particles. These positively charged particles formed by the removal of electrons from the gas atoms are called positive rays.

Characteristics of a proton

Mass

A proton is actually a hydrogen atom, which has lost its electron. Since the mass of an electron is small, the mass of a proton is equal to the mass of a hydrogen atom. As the mass of hydrogen atom is 1 a.m.u., the relative mass of a proton is 1 a.m.u. The mass of a proton is 1840 times that of an electron. The absolute mass of a proton is 1.6 x 10-24 gram.

Charge

The proton is equal and opposite to the charge of an electron. So the absolute charge of a proton is 1.6 x 10-19 coulomb of positive charge. This being the smallest positive charge carried by any particle, it is taken as 1 unit positive charge. The relative charge of a proton is +1 (plus one).

Effect of low pressure in the discharge tube

When the gas atoms in the discharge tube are at atmospheric pressure they collide with the electrons preventing them from reaching the anode. As no electrons reach the anode no current flows through the discharge tube. When the gas pressure is very low there are few gas atoms in the discharge tube. As such there is no hindrance to the movement of electrons and the gas conducts electricity.