The lowest frequency of light that will cause the emission of photoelectrons from the surface of a metal (for which work function is 1.65 eV) will be
Options
(a) 4×10¹⁰ Hz
(b) 4×10¹⁴ Hz
(c) 4×10¹¹ Hz
(d) 4×10¹⁵ Hz
Correct Answer:
4×10¹⁴ Hz
Explanation:
Maximum wavelength (in Å) = 12375 / ɸ (in eV)
⇒ λ₀ = 12375 / 1.65 = 7,500 Å = 7.5 × 10⁻⁷ m
Hence minimum frequency = ʋ₀ = c / λ₀
⇒ ʋ₀ = (3 × 10⁸) / (7.5 × 10⁻⁷) = 4 × 10¹⁴ Hz