Answer the following:
The threshold wavelength for two photosensitive surfaces A and B are $$\lambda_1$$ and $$\lambda_2$$, respectively. What is the ratio of the work functions of the two surface?
Given,
Threshold wavelength of
Surface, $$A = \lambda_1$$
Surface, $$B = \lambda_2$$
We know that,
work function, $$\phi = \dfrac{h C}{\lambda_{th}}$$
$$\phi \, \propto \dfrac{1}{\lambda_{th}}$$
$$\dfrac{\phi_A}{\phi_B} = \dfrac{\lambda_{th \, B}}{\lambda_{th \ A}} = \dfrac{\lambda_2}{\lambda_1}$$