The photoelectric effect is best demonstrated with which metal, given that it has a very low work function?
- A. Caesium
- B. Iron
- C. Tungsten
- D. Platinum
Explanation
Caesium's work function is only about 2 eV, so ordinary visible light is enough to eject electrons, whereas tungsten and platinum need ultraviolet. This is why alkali metals are used in photocells and photomultipliers. The low value reflects how loosely the single outer electron of an alkali metal is held.
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