Estimating the uncertainty in the location or speed of a particle

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Jessica Esparza 2H
Posts: 130
Joined: Wed Sep 18, 2019 12:15 am

Estimating the uncertainty in the location or speed of a particle

Postby Jessica Esparza 2H » Sun Oct 13, 2019 4:20 pm

HW Question 1B.5
How would you go about answering the following question? I'm having trouble beginning it.

The y-ray photons emitted by the nuclear decay of a technetium-99 atom used in radiopharmaceuticals have an energy of 140.511 keV. Calculate the wavelength of these y-rays.

Christine Honda 2I
Posts: 116
Joined: Sat Sep 14, 2019 12:17 am

Re: Estimating the uncertainty in the location or speed of a particle

Postby Christine Honda 2I » Sun Oct 13, 2019 4:27 pm

You will need to use a combined version of these two equations
and E=hv and c=λv
1st we are given KeV units but we need to convert that to eV then to joules since energy is measured in joules.
Kilo means 1000 of whatever unit is used. Therefore we multiply 140.511*10^3
Also the conversion factor for eV to joules is 1eV=1.6022*10^{-19} J

E= (140.511 x 10^3 eV)(1.6022 x 10^-19 J/eV) = 2.251 x 10^-14 J
Then we can combine the equations in order to get the wavelength
equation.

The wavelength equation becomes
λ=hc/E

Therefore,
(6.626 x 10^-34 J*s)(2.99792 x 10^8 m/s)/(2.251 x 10^-14J) = 8.824 x 10^-12= 883 nm


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