Radiations of monochromatic waves of wavelength are made incident on the surface of metals with work functions ϕ1 and ϕ2 respectively (take λ as the wavelength). Which of the following relationships holds true?
(a) ϕ1=ϕ2
(b) ϕ1>ϕ2
(c) ϕ1<ϕ2
(d) ϕ1=ϕ2+λ
