The saturation current from a thoriated - tungsten cathode at 2000 K is 100 mA. What will be the saturation current for a pure-tungsten cathode of th esame surface area operating at the same temperature ? The constant A in the Rihardson- Dushman equation is 60×104Am−2K−2 for pure tungsten and 3.0×104Am−2K−2 for thoriated tungsten. The work function of pure tungsten is 4.5 eV and that of thoriated tungsten is 2.6 eV.

The saturation current from a thoriated - tungsten cathode at 2000 K i

1.	The saturation current from a thoriated - tungsten cathode at 2000 K is 100 mA. What will be the saturation current for a pure-tungsten cathode of th esame surface area operating at the same temperature ? The constant A in the Rihardson- Dushman equation is 60×104Am−2K−2 for pure tungsten and 3.0×104Am−2K−2 for thoriated tungsten. The work function of pure tungsten is 4.5 eV and that of thoriated tungsten is 2.6 eV.
Answer» The saturation current from a thoriated - tungsten cathode at 2000 K is 100 mA. What will be the saturation current for a pure-tungsten cathode of th esame surface area operating at the same temperature ? The constant A in the Rihardson- Dushman equation is $60 \times 10^{4} A m^{- 2} K^{- 2}$ for pure tungsten and $3.0 \times 10^{4} A m^{- 2} K^{- 2}$ for thoriated tungsten. The work function of pure tungsten is 4.5 eV and that of thoriated tungsten is 2.6 eV.

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