## 1.33 [ENDORSED]

$\lambda=\frac{h}{p}$

204917020
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### 1.33

The velocity of an electron that is emitted from a metallic surface by a photon is 3.6 x 10^3 km x s^-1.

a) what is the wavelength of the ejected electron?

In the solutions, they use lambda= h/mv. I just don't understand how the units for mass (kg) cancel out? There's not other mass units in the equation so how is kg not in the answer?

Tiffany Chen 1A
Posts: 36
Joined: Fri Apr 06, 2018 11:02 am
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### Re: 1.33  [ENDORSED]

There's a kg "hidden" in h. The units for h are J*s and a Joule is the same as kg*(m^2)*(s^-2). Taking this into account, the kg from h will cancel with the kg from mass, and the other units also cancel until you're left with meters.