18. ••• In a mass spectrometer, a beam of protons enters a magnetic field. Some protons make exactly a onequarter circular arc of radius 0.50 m. If the field is always perpendicular to the proton’s velocity,

(a) what is the field’s magnitude if exiting protons have a kinetic energy of 10 keV?

(b) How long does it take the proton to complete the quarter circle?

(c) Find the net force

(magnitude) on a proton while it is in the field.

direction is shown.

(b) If in each case the wire is a straight segment 15 cm long carrying a current of 5.5 A, and is in a field whose strength is 1.0 mT, determine the magnitude of the magnetic force.