Metals and have work functions and respectively

PHYSICS · Multi-part · CBSE · Physics · Dual Nature of Radiation and Matter · Dual Nature of Radiation and Matter

Problem

Metals PP and QQ have work functions 2.0 eV2.0\,\text{eV} and 4.0 eV4.0\,\text{eV} respectively. A beam of white light containing wavelengths from 300 nm300\,\text{nm} to 700 nm700\,\text{nm} falls normally on samples of each metal. (i) Calculate the threshold wavelength for each metal. (ii) Identify the wavelength range, within the incident white-light spectrum, that can cause photo-emission from metal PP and from metal QQ separately. (iii) For incident light of wavelength 350 nm350\,\text{nm}, determine the ratio of the maximum kinetic energies of electrons emitted from metals PP and QQ. (Take h=6.63×10−34 J sh = 6.63\times10^{-34}\,\text{J s}, c=3.00×108 m s−1c = 3.00\times10^{8}\,\text{m s}^{-1}, 1 eV=1.6×10−19 J1\,\text{eV} = 1.6\times10^{-19}\,\text{J}.)

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