Question

The resistance of a discharge tube is
(a) non-ohmic
(b) ohmic
(c) zero
(d) both (b) and (c)

Answer 1

Hint: A gas-filled tube, also known as a discharge tube or historically as a Plücker tube, is an insulating, temperature-resistant envelope containing electrodes in a gas. Gas-filled tubes work by ionising the gas with an applied voltage high enough to produce electrical conduction through the Townsend discharge's underlying phenomenon.

Complete step by step solution:
Gas-discharge lamps, which include fluorescent lamps, metal-halide lamps, sodium-vapor lamps, and neon lights, are electric lights that use a gas-filled tube. In electric devices, specialised gas-filled tubes such as krytrons, thyratrons, and ignitrons are employed as switching devices. The voltage required to begin and maintain discharge is determined by the fill gas pressure and composition, as well as the tube shape. Despite the fact that the envelope is usually made of glass, power tubes are sometimes made of ceramics, and military tubes are frequently made of glass-lined metal. There are both hot cathode and cold cathode devices in use.
When the discharge tube is turned off, it has a very high resistance and when it is turned on, it has a very low resistance. V and I do not have a linear relationship; in fact, they do not have a linear relationship. That is why it is referred to as non-ohmic. An external resistor is necessary to restrict the current in a discharge tube (for example, a neon light). When the discharge tube is turned off, it has a very high resistance and when it is turned on, it has a very low resistance. V and I do not have a linear relationship; in fact, they do not have a linear relationship. That is why it is referred to as non-ohmic.

Note:
Hydrogen is utilised in tubes that are used for very quick switching, such as thyratrons, dekatrons, and krytrons, which require very steep edges. Hydrogen has considerably faster build-up and recovery periods than other gases. Hot-cathode hydrogen thyratrons are the most common kind. Hydrogen (and deuterium) can be stored in the tube as a metal hydride that is heated with an auxiliary filament; hydrogen can be used to replace cleaned-up gas and even to alter the pressure as needed for thyratron functioning at a certain voltage by heating such a storage element.