Not enough gas to support ionization.
The cathode dark space is dark because it contains very few electrons and ions, so there are not enough collisions happening to produce visible light. The low electron density in this region prevents the formation of plasma, which is necessary for light emission. As a result, the cathode dark space appears dark compared to other regions in the discharge tube.
Argon is used in the Geiger-Muller tube as a quenching gas to stop the discharge of ions after each pulse. Keeping argon at low pressure allows for efficient quenching of the ionization process. Higher pressure could interfere with the detection process by preventing the resetting of the tube after each detection event.
A discharge tube is a type of gas-filled tube that emits light when an electric current passes through it, commonly used in neon signs or plasma displays. On the other hand, a tube light is a type of fluorescent lamp that uses a phosphor coating inside a glass tube to produce light. While both types of tubes rely on gas and electric current to produce light, they differ in their construction and application.
A closed vessel having electrodes at either end and containing agas at low pressure. When a sufficient voltage is applied to theelectrodes, an electric current flows through the gas. Dischargetubes can be used to prevent current flow below a certainvoltage; they can also function as lamps by the use of ionizinggas, which glows when current flows through the tube.
The spectrum emitted by a discharge tube typically consists of discrete lines corresponding to the characteristic emission wavelengths of the elements or gases inside the tube. This emission spectrum results from the de-excitation of electrons in the atoms or molecules within the tube when they return to lower energy levels, emitting photons of specific energies. This emission pattern is unique to each element or gas, enabling scientists to identify the substances present in the discharge tube.
why it is necessary to decrease the pressure in the discharge tubbe to get cathode rays
why it is necessary to decrease the pressure in the discharge tubbe to get cathode rays
Glow appears in a discharge tube due to electrons colliding with gas atoms, exciting them to higher energy levels. When the excited atoms return to their ground state, they release photons of light, creating the glow.
When the pressure is reduced in a discharge tube, the mean free path of the gas molecules increases. This allows the gas molecules to gain more energy and move freely, colliding with the charged particles in the discharge tube and facilitating the flow of electric charge. As a result, the gases become partially ionized, creating a conductive path for the electricity.
cathode rays can't travel in air
because gases do not conduct electricity under normal pressure so at pressure of 0.1-0.001 mmHg with very high potential difference of 5000 to 10000 volts gases conduct electricity and produce fluorescence on the wall of discharge tube and it also avoid the collision of cathode rays with the positive rays
The cathode dark space is dark because it contains very few electrons and ions, so there are not enough collisions happening to produce visible light. The low electron density in this region prevents the formation of plasma, which is necessary for light emission. As a result, the cathode dark space appears dark compared to other regions in the discharge tube.
The question cannot be answered sensibly because argon is used!
It depends on the experiment, of course, but a discharge tube contains ionized atoms, while an incandescent simply has glowing metal. The former is, for most experiments, a lot more interesting.
If it's a *Crookes* tube you're asking about, it's a discharge tube because the applied electrical field causes ionization and a resulting discharge of energy in the form (mostly) of light, depending on the gas or gases in the tube.
Argon is used in the Geiger-Muller tube as a quenching gas to stop the discharge of ions after each pulse. Keeping argon at low pressure allows for efficient quenching of the ionization process. Higher pressure could interfere with the detection process by preventing the resetting of the tube after each detection event.
If the pressure in the discharge tube is nearly zero, there are very few gas particles present to ionize and create a conductive path for the electrons. This lack of gas particles results in very low conductivity and can prevent conduction from taking place in the Thomson experiment to determine the specific charge of an electron.