Atomic Structure: Practice Problem & Solution
The electron in the hydrogen atom jumps from excited state (n = 3) to its ground state (n = 1) and the photons thus emitted irradiate a photosensitive material. If the work function of the material is 5.1 eV, the stopping potential is estimated to be: (the energy of the electron in $n^{th}$ state) (2010 Mains)
Solution Explained:
To solve this problem, we apply the core principles of Atomic Structure. Understanding the underlying formula is key to arriving at the correct answer below:
Energy of emitted photon $E = E_3 - E_1 = -1.51 - (-13.6) = 12.09 eV$. Using Einstein's photoelectric equation, max kinetic energy $K_{max} = E - \phi = 12.09 - 5.1 = 6.99 eV \approx 7 eV$. Hence, the stopping potential is $7 V$.
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