Why does electric discharge takes place at low pressure and high potential difference?
Low pressure means that less number of gas molecules is present in the discharge tube. … Moreover, high voltage increases the kinetic energy of the electrons which in turn increases the probability of removal of electrons form the gaseous molecules.
Why does electric discharge occurs at low pressure?
Actually electric discharge takes place at low pressure because a small electric field is required. We know that at high altitude, pressure is very low with respect to low altitude for some electric field set – up in the atmosphere, the electron discharge takes place at high altitude but not at low.
Why does gas conduct only at low pressure and high voltage?
Due to which gases can’t conduct electricity at high pressure. At low pressure molecules of gas are far from each other due to which gas molecules have enough mean free path to accelerate. This means gas particles will acquire enough velocity and hence kinetic energy for the ionization of other molecules.
Why does the gas in a gas discharge tube need to be at low pressure in order for the gas to emit light when an electric current is passed through the tube?
1: Gas discharge tubes are enclosed glass tubes filled with a gas at low pressure, through which an electric current is passed. Electrons in the gaseous atoms first become excited, and then fall back to lower energy levels, emitting light of a distinctive color in the process.
Why does dark space appear in the discharge tube at low pressure?
A discharge tube appears dark when evacuated to extremely low pressure . … Because at low pressure , collisions between electrons and molecules becomes very low . The molecules remain unexcited and hence , they do not emit any light.
What happens when electric current is passed through a gas at low pressure?
When an electric current is passed through a gas, the gas emits light. … When a voltage is applied to the two electrodes and the pressure of the gas in the tube is reduced, eventually a pressure is reached at which a current flows, and the gas begins to glow.
Can a vacuum conduct electricity?
No, because vacuum is not a material object. The word conductor was meant for material bodies. It is not usually used to describe vacuum, because vacuum is not merely a different body from metal or dielectric, but it is a different concept – a lack of matter.
Why do gases have low pressure?
Generally, a gas behaves more like an ideal gas at higher temperature and lower pressure, as the potential energy due to intermolecular forces becomes less significant compared with the particles’ kinetic energy, and the size of the molecules becomes less significant compared to the empty space between them.
How does pressure affect electron movement in a gas?
The gas molecules are moving and are a certain distance apart from one another. An increase in pressure pushes the molecules closer together, reducing the volume. If the pressure is decreased, the gases are free to move about in a larger volume.
What is the optimum conditions required to study the condition of electricity through gases?
low pressure and high voltage.