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?

You need the low pressure in the tube so that the passage of the beam of electrons is not impeded very much by collision with air molecules. You need a reasonably high accelerating voltage to give the electrons enough kinetic energy to make the fluorescent screen glow when the electrons hit the screen.

Why discharge tube does not take place at very low pressure?

It is because when the gas is at very low pressure positive charged ions are not available to eject out the electron from the cathode hence the discharge current stops.No, vacuum cannot conduct electricity.

How can gases be made to conduct electricity?

In short, gases can conduct electricity, but they are considered insulators for the most part. Gas on its own cannnot conduct electricity but it can be made to conductor electricity by subjecting it under LOW PRESSURE and HIGH VOLTAGE.

Why do gases conduct at low 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. And this is why gases conduct electricity at low pressure.

Why does electric discharge occurs at low pressure?

Actually electric discharge takes place at low pressure because a small electric field is required. It was found that cathode when an electric field was applied perpendicular to the length of the discharge tube the cathode rays were found to be moving in a direction opposite of electric field.

Why does gas discharge occur at low pressure?

Low pressure means that less number of gas molecules is present in the discharge tube. If the number of molecules is very less, the collisionws between the electrons which move towards the anode with a high velocity and the gas molecules and formation of cathode rays takes place.

Why does electric discharge through gas take place 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.

Do gases conduct electricity at low pressure?

At low pressure molecules of gas are far from each other due to which gas molecules have enough mean free path to accelerate. As the ionization of molecules will occur there will be free electrons as we know that free electrons conduct electricity. And this is why gases conduct electricity at low pressure.

Under which of the following conditions do gases conduct electricity?

Gasses are usually made to conduct electricity (and possibly glow) when they are subjected to low pressure and quite high potential difference (or voltage). So, the ultimate condition for electrical conduction of gasses is LOW PRESSURE and HIGH VOLTAGE.

When electricity passes through a gas element in a discharge tube?

The light emitted by a gas, when an electric current flows through it, results from collisions between atoms in the gas and electrons of the current. When a voltage is applied to the two electrodes of a gas discharge tube, an electric field is created between the electrodes.

Do different gases taken in the discharge tube at the same pressure give electric discharge at the same potential?

If different gases are filled turn by turn at the same pressure in the discharge tube the discharge in them takes place at the same potential.