Finding de Broglie wavelength from energy

[robertjford80]

Homework Statement

The Attempt at a Solution

I don't see how they got sqrt(1.5/E) I tried it like this

Not the right answer.

 

[cepheid]

Homework Statement

The Attempt at a Solution

I don't see how they got sqrt(1.5/E) I tried it like this

Not the right answer.

It looks like you took the square root of h/(√2m) when you should have done the exact opposite: you should have squared it. Here's the reason. If:$$\sqrt{1.5} = \frac{h}{\sqrt{2m}}$$then$$1.5 = \frac{h^2}{2m}$$

I computed h^2/(2mE), and I plugged in a value of E = 1 so that I would get the same numerical answer as they did. I also had Google express it in nm^2 instead of m^2, so that the answer would be the same as theirs:

Google Calculator link

 

[robertjford80]

cool, i got it now.