Question

Let’s design a velocity selector device for a mass spectrometer. a.Illustrate the device and explain how it works. b.The electric field inside the device will operate at a level of 12.0E3 V/m. What will be the force on an ionized Calcium atom (q = +2 e) as it moves through the selector?c.If the magnetic field inside the device operates at a level of 0.250 T, what velocity will the device select?d.Explain what happens to negative ions travelling above or below the selection spe

Answer 1

A) A velocity selector is a device having a region where there is a uniform electric field and a uniform magnetic field. The fields are perpendicular to one another and perpendicular to the initial velocity of the charged particles that are passing through the region.
The force exerted on a charged particle by the electric field is given by:
F = qE
The magnitude of the force exerted by the magnetic field is

F = qvB, as long as the velocity is perpendicular to the field.
The principle behind this device, if the two forces are equal and opposite, the net force is zero, and the particle passes through the region without changing direction. Since the magnetic force is speed-dependent, however, any charges traveling faster or slower than the ones that go straight through will be deflected one way or another out of the beam.

Hence the velocity of the charged particle is given by,

B) Given,

C) Given,

D) If a negative ions speed is above or below the velocity selectors selected speed, it will be absorbed by the positive plate.