Radiation of wavelength 200 nm is incident on a photosensitive surface of work function 4·2 eV. The kinetic energy of fastest photoelectrons emitted from this surface will be close to :
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Memorize the value of \(hc\) as \(1240\text{ eV}\cdot\text{nm}\). This constant allows you to convert any wavelength directly into photon energy via simple division, eliminating the need for slow multi-step scientific notation calculations involving \(6.63 \times 10^{-34}\) and \(3 \times 10^8\).