The uncertainty in determining the duration during which an electron remains in a particular energy level before returning to the ground state is 2.0 x 10\(...

Assessment: WAEC SSCE - Physics - 2011 (Essay) Subject: Physics

Question 1 Report

The uncertainty in determining the duration during which an electron remains in a particular energy level before returning to the ground state is 2.0 x 10\(^{-9}\)s. Calculate the uncertainty in determining its energy at that level. (\(\frac{h}{2 \pi}\) = h = 1.054 x 10\(^{-34}\)Js)

Answer Details

By Heisenberg's uncertainty principle for energy and time,

\[ \Delta E \,\Delta t \geq \frac{h}{2\pi} = \hbar. \]

Taking the limiting (minimum) case, the uncertainty in energy is

\[ \Delta E = \frac{\hbar}{\Delta t} = \frac{1.054\times10^{-34}}{2.0\times10^{-9}}. \]

\[ \Delta E = 5.27\times10^{-26}\,\text{J}. \]

The uncertainty in determining the energy of that level is about \(5.27\times10^{-26}\,\text{J}\).

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