7/26/2023 0 Comments Neon cathode![]() The applications of neon lamps are given below − Neon lamps have small range of color spectrum. Neon cannot be used for ordinary lighting purposes like domestic lighting, etc. The main disadvantages of the neon lamps are given as − ![]() These lamps consume less amount of electricity. The neon lamps are available in miniature configuration. The primary advantages of the neon lamps are as follows − Therefore, these types of neon lamps are suitable for high operating voltage and low current applications. Hence, a continuous glow from the lamp is achieved. When AC supply is used, each electrode will turn positive and negative alternatively. Therefore, the lamp current for a standard neon lamp is less than 1 mA or fir a high brightness lamp is up to 2.5 mA. ![]() The strength of electric field near the cathode is very high and the ions under the influence of stray field will gain a lot of momentum which will cause disintegration of the cathode.Ī very small lamp current will give flickering of the gas discharge and a high lamp current will give a bright stable discharge, but life will be shorter and blackening of the envelope will occur. In order to discharge the neon gas, it requires a voltage equal to 1.5 to 2 times of the normal operating voltage. For this purpose, these require a very high voltage depending upon the distance between the electrodes. In the neon lamps, the cathode is heated for emission of electrons. Some important points about the working of neon lamp are listed below − When the excited neon atoms and ions come to their ground state, they give off light. On collision, a part of the energy is transferred from the electrons to the neon atoms and the neon atoms get excited. These electrons get accelerated by the electric field and collide with the neon atoms. When a high electric power supply is connected to the neon lamp, the cathode terminal starts emitting the electrons. Also, a series resistance of about 2000 ohms is mounted inside the cap. The glass envelope is filled with the neon gas at a pressure of about 8 torr. The neon lamp has two closely spaced electrodes, but not touching each other, in the form of thick parallel wire spiral or flat plate sealed within a soft glass envelope. The construction of a typical neon lamp is shown in the figure. “Electrons are emitted from cathode by subjecting the surface of the cathode to very high electric voltage so that the electrons are forcibly ejected from the orbits of the atoms against the nuclear centripetal forces.” Construction of Neon Lamp The working principle of the neon lamp is as follows − A miniature gas discharge lamp in which the electrical discharge takes place through a mixture of gases containing a large proportion of neon gas is known as neon lamp.
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