Gases under atmospheric pressure are generally poor conductors of electricity. However, when the gas pressure inside a discharge tube is lowered to approximately under a high potential difference, electrical conduction readily occurs. What is the primary physical reason for this increase in electrical conductivity at reduced pressures?
- The mean free path of ions increases, enabling them to gain sufficient kinetic energy to produce collisional ionization.Cevap
- BThe frequency of molecular collisions increases significantly, generating thermal ions spontaneously.
- CThe gas density increases at low pressure, providing a greater number of charge carriers per unit volume.
- DNeutral gas molecules decompose spontaneously into electrons without requiring collision energy.
Cevap
The increased conductivity at low pressures occurs because the mean free path of free ions increases, allowing them to accelerate under the high electric field and gain enough kinetic energy to cause ionization by collision with neutral gas atoms.
The correct option correctly states that reducing gas pressure increases the mean free path of ions. Under high applied potential differences, these ions travel longer distances uninterrupted, acquiring enough kinetic energy to ionize neutral gas molecules upon impact and causing electrical breakdown.
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Collisional Ionization and Mean Free Path in Gas Discharge