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Old CRT tv's use vacuum tubes and they get hot, but how does the glass get hot when the inside is under a vacuum and therefore shouldn't transfer any heat?
The vacuum tube plate dissipation (plate voltage times plate current) is often greater than the heater (or filament) power dissipation.
A vacuum tube, also known as a thermionic valve, is an electronic component that controls the flow of electrons in a circuit. It consists of a glass tube containing metal components and is used for amplification, switching, and rectification of electrical signals.
A vacuum tube gets hot through the process of thermionic emission. This occurs when a filament or cathode within the tube is heated, causing electrons to be released from its surface and creating a cloud of electrons around it. As the electrons move towards the anode, they collide with other molecules in the tube, generating heat.
A vacuum tube needs to get hot in order to function properly. The heat allows for thermionic emission to occur, which is necessary for the tube to control the flow of electrons in a circuit. Without this heat, the tube would not be able to amplify or switch electrical signals.
The temperature of a vacuum tube varies depending on its design and purpose, but it typically ranges from 1500 to 2000 degrees Celsius. The exact temperature also depends on the current flowing through the tube and the type of filament or cathode used.
Yes, there are some risks associated with a vacuum tube getting hot. The high temperatures can cause the tube to degrade over time, shortening its lifespan. There is also a risk of electrical shock if proper precautions are not taken while handling a hot vacuum tube. It is important to follow safety guidelines and use protective equipment when working with vacuum tubes.