Practice portal › Dual Nature of Matter and Radiation › Einstein's Photoelectric Equation and Work Function
Asked in GUJCET 2016 · Work function and the photoelectric equation
Given: λ₀ = 6800 A = 6.8×10⁻⁷ m, h = 6.625×10⁻³⁴ J s, c = 3×10⁸ m s⁻¹.
Idea: at the threshold wavelength a photon has just enough energy to free an electron, so φ₀ = (hc)/(λ₀).
φ₀ = (6.625×10⁻³⁴×3×10⁸)/(6.8×10⁻⁷) = (1.9875×10⁻²⁵)/(6.8×10⁻⁷)
φ₀ = 2.92×10⁻¹⁹ J
So the work function is about 2.9×10⁻¹⁹ J: the blank is 2.9.
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