Question 2.12: Electrons are emitted with zero velocity from a metal surface when it is exposed to radiation of wavelength 6800 Å. Calculate the threshold frequency (ν0) and work function (W0) of the metal.

Question 2.12: Electrons are emitted with zero velocity from a metal surface when it is exposed to radiation of wavelength 6800 Å. Calculate the threshold frequency (ν₀) and work function (W₀) of the metal.

Question 2.12: Electrons are emitted with zero velocity from a metal surface when it is exposed to radiation of wavelength 6800 Å. Calculate the threshold frequency (ν₀) and work function (W₀) of the metal.
Answer 2.12: Threshold wavelength of radiation (Λ₀) = 6800 Å = 6800 × 10^–10 m = 6.8 × 10^–7m
Threshold frequency (ν₀) of the metal
ν₀ = c/Λ₀
c = 3 × 10⁸ m/s
ν₀ = 3 × 10⁸/6.8 × 10^–7m
Thus, the threshold frequency (ν₀) of the metal is 4.41 × 10¹⁴ s ^–1.
Hence, work function (W₀) of the metal = hν₀
= (6.626 × 10^–34 Js) (4.41 × 10¹⁴ s^–1) = 2.922 × 10^–19 J
work function (W₀) = 2.922 × 10^–19 J