Time estimation - mass spectrometer

[Lindsayyyy]

Hi everyone

Homework Statement

I want to separate isotopes of uranium with some kind of a mass spectrometer. The isotopes are
Mass numbers 95
Atom numbers 235 and 238

Question:

How long does it take to extract 1kg of the 235 isotope if I have a ray of charged ions (charge = e) when the beam current is I=1mA ?

Homework Equations

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The Attempt at a Solution

I searched for the mass of an atom of uran (238.0289 u). Then I calculated how much atoms I have by dividing the mass 1kg by the mass of one atom.

The euqation for the current is:
$$I= \frac {eN}{t}$$

wheres e is the charge of an electron
N is the number of atoms
and t the time.

Now I solved the equation for t and used the given numbers.

Is this attempt right?
(my solution is t=1.13*10^5)

Thanks for your help.

 

[mfb]

I get 4*10⁸ seconds or about 13 years.