What is the magnitude of the force exerted?

Question

A particle of mass 1.1454X10^-25 kg. and charge of magnitude 4.8 x 10^-19 C is accelerated from rest in the plane of the page through a potential difference of 218 V between two parallel plates. The particle is injected through a hole in the right-hand plate into a region of space containing a uniform magnetic field of magnitude 0.138 T oriented perpendicular to the plane of the page. The particle curves in a semicircular path and strikes a detector.

What is the magnitude of the force exerted on the charged particle as it enters the region of the magnetic field B? Answer in N

Answer 1

Force (Lorentz) = q v b * sin theta (and theta =90 therefore can be ignored)

so you just have: F = q v b

From the velocity I worked out before-: 42744.99533 ms^-1

F = 4.8 x 10^-19 * 42744.99533 * 0.138 = 2.83142849 x 10^-15 Newtons

Sounds about right for a particle of this mass. You should realise the faster a particle travels in a magnetic field the more force it is subjected to.