How does a discharge tube work?

A gas- discharge tube is usually a glass tube with two electrodes sealed through its walls. 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.

How the emission spectrum of hydrogen is obtained experimentally?

Emission Spectrum of Hydrogen. When an electric current is passed through a glass tube that contains hydrogen gas at low pressure the tube gives off blue light. When this light is passed through a prism (as shown in the figure below), four narrow bands of bright light are observed against a black background.

What is discharge tube in physics?

: an electron tube which contains gas or vapor at low pressure and through which conduction takes place when a high voltage is applied.

Why does a hydrogen discharge tube give off pink light when exposed to electricity?

A discharge of energetic electrons through the gas causes collisions of electrons with the gas atoms, resulting in electrons in the gas atoms being excited to higher energy states. The electrons then return to their normal (ground state) energies by emitting electromagnetic radiation. That is why you see colors.

What is a hydrogen discharge tube?

A hydrogen discharge tube is a slim tube containing hydrogen gas at low pressure with an electrode at each end. If a high voltage (5000 volts) is applied, the tube lights up with a bright pink glow. If the light is passed through a prism or diffraction grating, it is split into its various colors.

What is discharge tube explain with diagram?

Discharge tube is also called “CROOCK TUBE”. It is made of a glass tube which consists of two metallic plates. One plate is connected to positive terminal of high voltage power supply and the other to negative terminal.

Why does hydrogen spectrum have 4 lines?

Although hydrogen has only one electron, it contains many energy levels. When its electron jumps from higher energy level to a lower one, it releases a photon. Those photons cause different colours of light of different wavelengths due to the different levels. Those photons appear as lines.

Why are only 4 lines seen in the hydrogen emission spectrum?

This is explained in the Bohr model by the realization that the electron orbits are not equally spaced. The electron energy level diagram for the hydrogen atom. He found that the four visible spectral lines corresponded to transitions from higher energy levels down to the second energy level (n = 2).

What is discharge tube experiment Class 9?

Experimental set up 1) It consist of a long cylindrical tube sealed at both ends and is fitted with two metal electrodes. 2) The electrodes are connected to source of high voltage. 3) The tube is connected to a vacuum pump as to increase or decrease the pressure. 4) The discharge tube is filled with air.

Why does hydrogen only emit 4 colors?

What happens that causes the hydrogen atom to emit light?

The energy in a hydrogen atom depends on the energy of the electron. When the electron changes levels, it decreases energy and the atom emits photons. The photon is emitted with the electron moving from a higher energy level to a lower energy level.

How does a hydrogen discharge tube work?

Why do we need a hydrogen discharge tube?

In our introductory labs we use a variety of gas discharge tubes for observing spectra (hydrogen, helium, argon, neon, mercury). We have to replace the hydrogen tubes often because they “wear out” like this. The other tubes usually last until someone breaks them.

Why are the lines on my hydrogen spectra tube so dim?

After a couple of years, the tubes leak and air gets mixed with the hydrogen. This causes them to get dim and the weaker lines are almost impossible to see. It has nothing to do with the power supply and everything to do with how new the tube it and how many hours of use it has seen.

Why are the hydrogen spectra red and green?

But for our source we can only able to see H-alpha (Red) and H-beta (Blue-ish-Green) lines. The possible reason behind this is that our hydrogen source is very dim (intensity of light is small). The voltage of 2000V is applied across the gas discharge tube.

How did J J Balmer discover the spectrum of hydrogen?

The Balmer formula J.J. Balmer discovers (1885) that the quantized (discrete) visible emission spectrum of the hydrogen follows a mathematical formula: He found the following expression for the wavelength of the absorption lines completely empirically. He did not provide any physical explanation for it: Different values of n

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