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## Homework Statement

What is the de Broglie wavelength of a neutron travelling with a momentum equal to [tex]300 \frac{\text{MeV}}{\text{c}}[/tex]?

## Homework Equations

[tex]\lambda = \frac{h}{p}[/tex]

## The Attempt at a Solution

[tex]p = \frac{300 \cdot \left( \left(1\times10^6 \right) \times \left(1.602\times10^{-19} \right) \right)}{2.998\times10^8}[/tex]

[tex]= 1.603\times10^{-19} \text{ kgms}^{-1}[/tex]

[tex]\lamda = \frac{6.626\times10^{-34}}{1.603\times10^{-19}}[/tex]

[tex]= 4.133\times10^{-15} \text{ m}[/tex]

That's what I get, but the answer is given as 1.38x10^{-23}m.

By inserting this given answer into the equation, I get a value of 4.801x10^{-11} for p, which I can only get by the following:

[tex]300 \frac{\text{MeV}}{\text{c}} = 300 \cdot \left( \left( 1\times10^6 \right) \times \left(1.602\times10^{-19} \right) \right)[/tex]

which ignores the c.

Is the given answer wrong, or am I missing something important?

This doesn't make any sense to me.