18.  Suppose that an ion source in a mass spectrometer produces doubly ionized gold ions (Au2+), each with a mass of 3.27 x 10-25 kg. The ions are accelerated from rest through a potential difference of 1.00 kV. Then, a 0.500-T magnetic field causes the ions to follow a circular path. Determine the radius of the path.

 

The velocity of the gold ions is found by conservation of energy

 

 

 

 

 

Now by considering the sum of the radial forces we get

 

Solve for R

 

 

 

Alternatively we could have combined equations and only plugged numbers in once

 

 

 

 

 

As it should be!!

 

 

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This page last updated on June 21, 2018