Why is light produced in electric discharge 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 an electric discharge does 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.

How does a electric discharge produce light?

Light is often produced when an electric current passes through a gas. We see a burst of this light in the sparks of static electricity or lightning. Several types of lamps produce light by establishing a permanent electric arc in a gas. This process is known as electric discharge, or gaseous discharge.

Why the electrical discharge through the gases could be observed only at very low pressure and at very high voltage?

1)It can only be observed so because air is a poor conductor and on such harsh conditions(high voltage and low pressure) air conducts electricity.

How does electric discharge takes place through gas?

Electric discharge in gases occurs when electric current flows through a gaseous medium due to ionization of the gas. The properties of electric discharges in gases are studied in connection with design of lighting sources and in the design of high voltage electrical equipment.

How is light produced in discharge or arc lighting?

A xenon arc lamp is a specialised type of gas-discharge lamp, an electric light that produces light by passing electricity through ionised xenon gas at high pressure to produce a bright white light that closely mimics natural sunlight.

What is gas discharge sources?

Gas-discharge lamps are a family of artificial light sources that generate light by sending an electric discharge through an ionized gas, a plasma. Typically, such lamps use a noble gas (argon, neon, krypton, and xenon) or a mixture of these gases. Gas discharge lamps can produce a wide range of colors.

When electricity passes through a gas element in a discharge tube light is given off what is the cause of this phenomenon?

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.

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.

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

Why a discharge tube appears dark when evacuated to very 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.