Question

home / study / questions and answers / science / physics / a group of particles is traveling in a magnetic ... Your question has been answered! Rate it below. Let us know if you got a helpful answer. Question A group of particles is traveling in a magnetic field of unknown magnitude and direction. You observe that a proton moving at 1.50 km/s in the +x-direction experiences a force of 2.06×10−16 N in the +y-direction, and an electron moving at 4.20 km/s in the −z-direction experiences a force of 8.40×10−16 N in the +y-direction.


Part A What is the magnitude of the magnetic field? Part B What is the direction of the magnetic field? (in the xz-plane) Part C What is the magnitude of the magnetic force on an electron moving in the −y-direction at 3.70 km/s ? Part D What is the direction of this the magnetic force? (in the xz-plane)

Answer 1

The z component of the magnetic field is
-2.06x10^-16N/(1.602x10^-19C x 1.50 x 10³ m/s = 0.8572T
The x component of the magnetic field is
8.40 x 10^-16N / (1.602x10^-19C x 4.20 x 10³ m/s) = 1.248 T,
the force on the electron acts in the +y direction,
then the x component of the magnetic field is also positive,
since (-)(-k) x (i) = +j.

magnitude of the magnetic field is

and its direction is in the x-z plane at

away from the + x-axis

and 55.53⁰ away from the + z-axis.

(b) In doing this part, I will again assume that the electron moving in the -z direction
was deflected in the +y direction.
F = qv x B
= (-1.602 x 10^-19C)(-3.7 x 10³ m/s j) x (1.248 i + 0.8572 k) T
= (-7.39 k + 5.0809 i) x 10^-16 N
The magnitude of this force is

N

= 8.96 x 10^-16 N
and its direction is in the x-z plane,
perpendicular to the magnetic field,
so 34.48 degrees away from the negative z axis
and 55.53 degrees away from the positive x axis.