mass spec: why does increasing velocity affect radius?

[tdod]

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Why isn't the particle's increased velocity counteracted by the increased magnetic force (since Fmagnetic = q v b sinø)

 

[goft20]

V and fmag have a direct relationship. So as one goes up the other does as well. I hate physics.


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[DenTony11235]

Why isn't the particle's increased velocity counteracted by the increased magnetic force (since Fmagnetic = q v b sinø)

Can you clarify what you mean?

A particle with a greater velocity will definitely experience a greater B, but what's that have to do with mass spec?

 

[Skizye]

In a mass spectrometer the magnetic field provides a conservative centripetal force. So mv^2/r = qvb, solve for r and you can see that v and r are directly related.

 

[gettheleadout]

Why isn't the particle's increased velocity counteracted by the increased magnetic force (since Fmagnetic = q v b sinø)

It's not "counteracted" because the F_mag vector is perpendicular to the particle velocity vector.