Question

One beam of electrons moves at right angles to a magnetic field. the force on these electrons is 4.9 x 10-14 newtons. a second beam travels at the same speed, but at a 30° angle with the magnetic field. what force is on these electrons?

Answer 1

Below are the choices that can be found elsewhere:

A. (4.9 × 10-14 newtons) · tan(30°) 
B. (4.9 × 10-14 newtons) · sin(30°) 
C. (4.9 × 10-14 newtons) · cos(30°) 
D. (4.9 × 10-14 newtons) · arctan(30°) 
E. (4.9 × 10-14 newtons) · arccos(30°)

Force is proportional to the angle made by the velocity with respect to the magnetic field. It is maximum when velocity is perpendicular to the magnetic field and minimum when the velocity is parallel to the magnetic field. It is proportional to sin of the angle. In this problem it will be proportional to sin(30)