- #1
Saitama
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Homework Statement
If the energy of H-atom in the ground state is -E, the velocity of the photo-electron emitted when a photon having energy EP strikes a stationary Li2+ ion in the ground state is given by:
(a)[itex]v=\sqrt{\frac{2(E_P-E)}{m}}[/itex]
(b)[itex]v=\sqrt{\frac{2(E_P+9E)}{m}}[/itex]
(c)[itex]v=\sqrt{\frac{2(E_P-9E)}{m}}[/itex]
(d)[itex]v=\sqrt{\frac{2(E_P-3E)}{m}}[/itex]
Homework Equations
E=W+K.E.
(W represents work function)
The Attempt at a Solution
Energy of H-atom in ground state, [itex]E_H=-E[/itex]
Energy of Li+2 ion in ground state, [itex]E_Li=-2.18*10^{-18}J*3^2=-9E[/itex]
[tex]K.E.=E-W[/tex]
[tex]\frac{1}{2}mv^2=E_P-(-9E)[/tex]
[tex]v=\sqrt{\frac{2(E_P+9E)}{m}}[/tex]
But the answer in the answer key is option (c).