An electron moves through a uniform magnetic field of magnitude with speed

PHYSICS · Single correct · AP · Physics C: Electricity and Magnetism · Magnetic Fields and Electromagnetism · Magnetic Fields and Electromagnetism

Problem

An electron moves through a uniform magnetic field of magnitude

0.40\,\text{T}

with speed

6.0\times10^{6}\,\text{m/s}

. In situation A the angle between the velocity and the field is

25^{\circ}

; in situation B it is

65^{\circ}

. What is the ratio

F_{\text{B}}/F_{\text{A}}

of the magnetic force magnitudes? (a) 0.47 (b) 2.1 (c) 1.0 (d) 4.6