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## Homework Statement

An electron moves with speed v=10

^{-4}c inside a one dimensional box (V=0) of length 48.5 nm. The potential is infinite elsewhere. The particle may not escape the box. What approximate quantum number does the electron have?

## Homework Equations

E

_{n}= n

^{2}[itex]\frac{\pi^{2}\hbar^{2}}{2ml^{2}}[/itex]

KE = [itex]\frac{mv^{2}}{2}[/itex]

9.1e

^{-31}kg / electron

6.2e

^{18}eV / J

## The Attempt at a Solution

I know that I need to find the kinetic energy of the electron and compare it with the various energies given by the first equation above in order to determine the value of n. However, I keep getting values for E that are far too small:

KE = [itex]\frac{mv^{2}}{2}[/itex] = [itex]\frac{1.9\times10^{-31} kg \times (3\times10^{4} m/s)^{2}}{2} \times 6.2\times10^{18} eV/J [/itex] = [itex]5.301\times10^{-4} eV[/itex]

This is far lower than the energies I get out of the first equation above, so I think that I'm missing something up to this point.

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