Register to reply

Magnetic fields

by athenaroa
Tags: fields, magnetic
Share this thread:
athenaroa
#1
Mar23-04, 02:52 PM
P: 11
A Fe+ ion is traveling at 200 m/sec in a direction 20 deg south of west at a point. The magnetic field at that point is 0.4 T directed at 10 deg west of south. What is the instantaneous magnetic force that acts on the Fe is how many newtons?
Phys.Org News Partner Physics news on Phys.org
Vibrational motion of a single molecule measured in real time
Researchers demonstrate ultra low-field nuclear magnetic resonance using Earth's magnetic field
Bubbling down: Discovery suggests surprising uses for common bubbles
Chen
#2
Mar23-04, 03:19 PM
Chen's Avatar
P: 1,004
The magnetic force on a charge that travels through a magnetic field is:
[tex]\vec F_m = q\vec V \times \vec B = q|V||B|\sin \alpha[/tex]
([itex]\alpha[/tex] being the angle between the field vector and the velocity vector of course.)
ZapperZ
#3
Mar24-04, 10:30 AM
Emeritus
Sci Advisor
PF Gold
ZapperZ's Avatar
P: 29,238
Originally posted by Chen
The magnetic force on a charge that travels through a magnetic field is:
[tex]\vec F_m = q\vec B \times \vec V = q|B||V|\sin \alpha[/tex]
([itex]\alpha[/tex] being the angle between the field vector and the velocity vector of course.)
I normally would not be picky on such things. However, it should be corrected that the general form of Lorentz force for the magnetic field term is proportional to q(v x B), not q(B x v).

Since the original question involves the exact vectorial direction of the force, and since cross products are not commutative, this can produce an error in the direction.

Zz.

Chen
#4
Mar24-04, 01:26 PM
Chen's Avatar
P: 1,004
Magnetic fields

Of course, I've corrected my post. Thanks for pointing my mistake out. Usually I just use the right-hand rule to find the direction of the magnetic force.


Register to reply

Related Discussions
Magnetic Forces on Current-Carrying Wires (in magnetic fields). Is answer correct? Introductory Physics Homework 2
Magnetic forces/magnetic fields Advanced Physics Homework 0
Magnetic Forces and Magnetic Fields (mass spectrometer) Introductory Physics Homework 8
Electric fields, magnetic fields and Lorentz frames Advanced Physics Homework 5
Magnetic fields inducing electric fields - turning on lightbulb with magnetic field Introductory Physics Homework 3