Coating of strontium oxide on a tungsten cath | vedclass

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(A) The coating of strontium oxide on a tungsten cathode reduces the work function of the surface. According to Richardson-Dushman equation,the thermi

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Work function decreases

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(A) The coating of strontium oxide on a tungsten cathode reduces the work function of the surface. According to Richardson-Dushman equation,the thermionic emission current density $J$ is given by $J = AT^2 e^{-\phi/kT}$,where $\phi$ is the work function. Since the work function $\phi$ decreases due to the oxide coating,the thermionic emission increases significantly at a given temperature.

Coating of strontium oxide on a tungsten cathode in a valve is good for thermionic emission because:

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