Question

Monochromatic radiation of wavelength nm (1 nm = 10^-9 m) from a neon lamp irradiates photosensitive material made of caesium on tungsten. The stopping voltage is measured to be 0.54 V. The source is replaced by an iron source and its 427.2 nm line irradiates the same photo-cell. Predict the new stopping voltage.

Answer 1

For neon lamp:

λ = 640.2 nm = 640.2 x 10^-9 m

V₀ = 0.54 V