Electrons are emitted with zero velocity from a metal surface when it is exposed to radiation of wavelength 6800 Å. Calculate threshold frequency v0 and work function w0 of the metal.

Since, K.E is zero, the energy of radiation is equal to the work function of the metal. Also, the threshold frequency is equal to the frequency of radiation.The threshold frequency is ν₀=ν=c/λ=3.0×10⁸m/s/6800×10⁻¹⁰m=4.41×10¹⁴/s.The work function is hν₀=6.626×10⁻³⁴×4.41×10¹⁴=2.92×10⁻¹⁹J.