Question

An upward force acts on a proton as it moves with a speed of 2.0 × 105 meters/second through a magnetic field of 8.5 × 10-2 tesla running from east to west. What is the force and direction of the force on the proton?
A. 2.7 × 10-15 N to the north
B. 2.7 × 10-15 N to the south
C. 1.7 × 10-14 N to the north
D. 1.7 × 10-14 N to the south
E. 1.7 × 10-14 N downward

Answer 1

magnetic force: F = qvB
where q is the charge (1.6 x 10^-19 C since it's a proton), v is the speed (given as 2.0 × 10^5 meters/second) and B is the magnetic field strength (given as 8.5 × 10^-2 tesla)

plug in and evaluate to find the magnitude of the force

now, to find the direction, use the right hand rule. using your right hand, point your index finger in the direction of the magnetic field; your middle finger at a right angle, in the direction of the proton's velocity, and your thumb will point in the direction of the force

diagram for reference: https://cdn.education.com/files/static/science-fair/effect-magnet-electron-beam-right/flemings-right-hand-rule.png