What is the direction of the magnetic force on the proton? What is the magnitude of the magnetic force on the proton?

A proton is traveling west, with speed 4 x 10^5 m/s. The proton encounters a magnetic field of 0.34 T going east, due to current running in a nearby wire.

1 Answer
Mar 8, 2016

Answer:

Magnitude of the magnetic force on the proton is understood as magnitude of the force experienced by the proton in the magnetic field which has been calculated and is #=0#.

Explanation:

Force experienced by a charge particle having charge #q# when it moves with velocity #vecv# in an external electric field #vecE# and magnetic field #vecB# is described by the Lorentz Force equation:

#vecF= q(vecE+ vecv times vecB)#

Given a proton moving West encounters a magnetic field going to East. As there is no external electric field, above equation reduces to
#vecF= qcdot vecv times vecB#

As the velocity vector of proton and magnetic field vector are opposite to each other, angle #theta# between the two#=180^@#.
We know that #sin180^@=0#.
Consequently the cross product vanishes.
#:.vecF=0#