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The figure below shows a vaccum tube containing electrodes made of different metals, 1 and 2 whose work functions are `phi_(1)` and `phi_(2)` The electrodes are illuminated simultaneously. The maximum kinetic energy of photoelectrons reaching plate 2 is 1 eV and maximum kinetic energy of photoelectrons reaching plate 1 is 3 eV. Assume that photoelectron emitted from either plate do not interact with each other `phi_(1)=1.5` eV and `phi_(2)=0.7` eV. Find wavelength (in nm) of the electromagnetic wave used |
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Answer» Correct Answer - `400` `K_(2max)=(hc)/lambda-phi_(1)-ev_(0)=1` `K_(1max)=(hc)/lambdaphi_(2)+ev_(0)=3` `(2hc)/lambda(phi_(1)+phi_(2))=4` `(2xx1240)/(4+2.2)=lambda` `lambda=400nm` |
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