Ultraviolet radiation of wavelength falls normally on a potassium surface

PHYSICS · Multi-part · A Level · Physics · Particles and radiation · Particles and radiation

Problem

Ultraviolet radiation of wavelength 250 nm250\,\text{nm} falls normally on a potassium surface. The work function of potassium is 2.30 eV2.30\,\text{eV}. Use h=6.63×10−34 J sh = 6.63\times10^{-34}\,\text{J\,s}, c=3.0×108 m s−1c = 3.0\times10^{8}\,\text{m\,s}^{-1} and e=1.6×10−19 Ce = 1.6\times10^{-19}\,\text{C}. (i) Convert the photon energy into electron-volt. (ii) Find the maximum kinetic energy of the emitted electrons in (a) joule and (b) electron-volt. (iii) Calculate the corresponding stopping potential.

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