Tungsten has work function 4.8 eV. We wish to use tungsten as pho… - Vidyadip

MCQ

Tungsten has work function $4.8\ eV$. We wish to use tungsten as photo$-$cathode with a $600\ nm$ wavelength. What shall we do?

A
Coat tungsten with Cesium
✓
Oxide coat tungsten
C
$\mathrm{Cu}_2 \mathrm{~O}_2$ be coated on tungsten
D
None of these

✓

Answer

Correct option: B.

Oxide coat tungsten

A photocathode usually consists of alkali metals with very low work function. The coating releases electrons much more readily than the underlying metal, allowing it to detect the low$-$energy photons in infrared radiation. To lowering the work function of the tungsten Oxide coating is used.

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