In a mass spectrometer, ions are directed into a magnetic field, where they curve and strike a detector. If a variety of singly ionized atoms travel at the same speed through the magnetic field, would you expect them all to be deflected by the same amount, or would different ions be bent to different amounts? Defend your answer.

Question

Mischief

Physics

10 September, 17:09

In a mass spectrometer, ions are directed into a magnetic field, where they curve and strike a detector. If a variety of singly ionized atoms travel at the same speed through the magnetic field, would you expect them all to be deflected by the same amount, or would different ions be bent to different amounts? Defend your answer.

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Answers (1)

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Makena Yates · Answer 1

the trajectory depends on the velocity and mass of the ions, therefore, they should be in different quantities

Explanation:

A mass spectrometer works based on the electrical force to accelerate the ions to a certain speed and the magnetic force to give a circular trajectory, let's use Newton's second law

F = m a

q v B = m v2 / r

r = (q / m) B / v

Here we can see that the radius of curvature of the ions depends on the velocity, but also on the mass of each of them. Therefore, even when they enter with the same speed they deviate in different trajectories depending on their mass.

The heavier ions will have smaller radii than the lighter ions

Consequently, the trajectory depends on the velocity and mass of the ions, therefore, they should be in different quantities