AIIMS 2019 Physics Threshold Wavelength MCQ Question

When light of wavelength λ is incident on the metallic surface, the stopping potential (V₁) is 3 V, indicating that the energy of the incident photons (E₁ = hν₁ = hc/λ) exceeds the work function (ϕ) by 3 eV. For the light of wavelength 2λ, the stopping potential (V₂) is 1 V, meaning E₂ = hν₂ = hc/(2λ) exceeds ϕ by 1 eV. By applying the photoelectric equation, we find that the threshold wavelength (λ₀) can be derived from the relationship between the stopping potentials and wavelengths, leading to λ₀ = 4λ. Other options are incorrect as they do not satisfy the energy balance derived from the stopping potentials and the corresponding photon energies.