Answer
1.4 T to the east.
Work Step by Step
The electron’s velocity is perpendicular to the magnetic field, so the magnetic force is maximum. The magnitude is given in equation 20–4.
$$F_{max}=6.2\times10^{-13}N =qvB=(1.60\times10^{-19}C)(2.8\times10^6m/s)B $$
The magnetic field has a magnitude of 1.4 T.
Use the right hand-rule, as described on page 566, to calculate the direction of the force on a positively-charged particle. Since this charge is negative, the force is opposite to the result given by the right-hand rule. Note: Some instructors advocate the use of a “left-hand rule” for negative charges, which also works.
The magnetic field is directed to the east.
