When photons of wavelength λ₁ are incident on an isolated sphere, the corresponding stopping potential is found to be V. When photons of wavelength λ₂ are used, the corresponding stopping potential is thrice that of the above value. If light of wavelength λ₃ is used then the stopping potential for this case:
O hc/e[1/λ₃ +1/λ₂-λ₁
O hc/e[1/λ₃ +1/2λ₂-2λ₁
O hc/e[1/λ₃ -1/λ₂-λ₁
O hc/e[1/λ₃ +1/2λ₂-λ₁