De Broglie problem (1 Viewer)

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1. The problem statement, all variables and given/known data
What is the length of a one-dimensional box in which an electron in the n=1 state has the same energy as a photon with a wavelength of 500 nm

2. Relevant equations

E=h^2/8mL^2 and E=hc/lambda

making it
L=sqrt( (h*lambda)/(8cm) )

3. The attempt at a solution

I plugged in for those numbers and did not come out with the correct number. any suggestions?
Are you sure that 8 should not be a 4?


The eightfold way is right here. 1/8=(L/2)^/2.
I think your first h should be hbar.
The energy if the first state of an indefinite one-dimensional box is:
Where m is the mass of the particle and L is the length of the box.
The photon has the energy given by
Where [tex]\lambda[/tex] is the wave length.
And therefore the length L is [tex]L=\sqrt{\frac{\pi\hbar\lambda{c}}{4m}}[/tex]
Last edited:

Shooting Star

Homework Helper
And therefore the length L is [tex]L=\sqrt{\frac{\pi\hbar\lambda{c}}{4m}}[/tex]
Which is wrong. It should be [tex]\sqrt{\frac{\pi\hbar\lambda}{4mc}[/tex], which is identical to what the OP psingh had written correctly. Replacing [itex]h[/itex] by [itex]2\pi\hbar[/itex] won't do any good.

Perhaps the OP made some arithmetical mistake...

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