In a discharge tube ionization of enclosed gas isproduced due to collisions between [2006]a)negative electrons and neutral atoms /moleculesb)photons and neutral atoms /moleculesc)neutral gas atoms/moleculesd)positive ions and neutral atoms/moleculesCorrect answer is option 'A'. Can you explain this answer?

Question

Answer

In a discharge tube, after being accelerated though a high potential difference the ions in the gas strike die cathode with huge kinetic energy. This collision liberates electrons from the cathode. These free electrons can further liberate ions from gas molecules through collisions. The positive ions are attracted towards the cathode and negatively electrons move towards anode. Thus, ionization of gas results.

Answer

Explanation:

In a discharge tube, the process of ionization occurs due to collisions between negative electrons and neutral atoms/molecules in the enclosed gas. Let's understand this in detail:

Discharge Tube:
A discharge tube is a glass tube filled with a gas at low pressure. It consists of two electrodes: a cathode (negative electrode) and an anode (positive electrode). When a high voltage is applied across these electrodes, it creates an electric field within the tube.

Ionization:
Ionization is the process of converting neutral atoms or molecules into charged particles called ions. In a discharge tube, ionization occurs when the electrons in the gas collide with neutral atoms/molecules.

Collision between Negative Electrons and Neutral Atoms/Molecules:
When a high voltage is applied to the discharge tube, the electric field accelerates the electrons towards the anode. As the electrons move towards the anode, they gain kinetic energy. When these fast-moving electrons collide with the neutral atoms/molecules in the gas, they transfer some of their energy to the atoms/molecules.

Energy Transfer:
During the collision, the transferred energy can be sufficient to remove one or more electrons from the atoms/molecules, resulting in the formation of positive ions. This process is known as ionization. The newly formed positive ions and the free electrons continue to undergo further collisions, leading to a cascade effect where more and more ions are formed.

Importance of Negative Electrons:
The negative electrons play a crucial role in the ionization process. They are highly mobile and carry a negative charge. As they gain energy and collide with neutral atoms/molecules, they transfer their energy and create positive ions. These positive ions can then be attracted towards the cathode (negative electrode), maintaining the flow of current in the discharge tube.

Therefore, the ionization of the enclosed gas in a discharge tube is primarily due to collisions between negative electrons and neutral atoms/molecules. This process leads to the formation of positive ions and the flow of electric current.

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