electron [N] moving in a magnetic field [up]

1. The problem statement, all variables and given/known data

A magnetic field of 0.0200 T (up) is created in a region

a. Find the initial magnetic force on an electron initially moved at 5.00 x 10^6 m/s [N] in the field

b. What is the radius of the circular path? Make a sketch showing the path of the electron.

2. Relevant equations

Fm = q v b sinΘ

Fc = (m v^2)/r

3. The attempt at a solution


F_M=q v β

F_M=(1.6*10^(-19) C)(5.00*10^6 m/s)(0.00200 T)

F_M=1.6*10^(-15) N

my issue is the direction of the force. how do you apply the right hand rule to a charged particle moving in the same direction as the field? doesn’t the particle need to travel perpendicular to the field to interact with it? because it’s an electron i know i have to reverse it or use the "left hand rule" but i’m still utterly confused since the particle is moving in the same direction as the field.


Fnet = Fm

in circular motion Fnet = Fc

Fc = Fm

(m v^2)/r = q v β

r = m v/q β

r = (9.1 * 1^-31 kg)(5.00 x 10^6 m/s)/(1.6 x 10^-19 C)(0.00200 T)

r = 0.142 m

r = 14.2 cm


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