Practice portal › Dual Nature of Matter and Radiation › Conceptual and Statement Questions on the Photoelectric Effect
Asked in GSEB Board July 2021 · Conceptual points of the photoelectric effect
Idea: an electron is emitted only if a single photon brings at least the work function, hf ≥ φ₀.
Zinc, cadmium and magnesium have work functions larger than 3.1 eV, the energy of a violet (400 nm) photon.
So no visible colour can eject electrons from them; only the shorter-wavelength ultraviolet photons carry enough energy.
Alkali metals such as sodium, potassium and caesium have smaller work functions and respond even to visible light.
So these metals responded only to ultraviolet light.
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