Physics Notes - Herong's Tutorial Notes - v4.01, by Herong Yang
Moving Charge Creating Magnetic Field
This section describes magnetic fields created by moving electric charges.
It was discovered by Hans Christian Oersted in 1820 that a moving electric charge creates a magnetic field, as illustrated by the following diagram from iitianacademy.com/ap-exam/ap-physics-c-electricity-and-magnetism-exam-revision/ ap-physics-c-em-12-2-magnetism-and-moving-charges-study-notes/:
Calculation of magnetic field created by a moving point charge can be done with the formula below:
where:
B is the magnetic field vector at (x, y, z)
q is the moving point charge
μ0 is the vacuum permeability (1.256637 × 10-6)
v is the velocity vector of the moving charge
r is the distance vector from point charge to (x, y, z)
× is the cross product operation of vectors
Electric current is made of fast moving positive charges. So it will create a magnetic field along its conducting wire. The diagram below shows magnetic lines representing the magnetic field created by the electric current in a straight wire. Each magnetic line is a perfect circle perpendicular to the wire.
Table of Contents
Introduction of Frame of Reference
Magnetic Force on Moving Charges
►Moving Charge Creating Magnetic Field
Biot-Savart Law for Magnetic Fields
Magnetic Fields of Current Carrying Loops
What Is Magnetic Dipole and Moment
Introduction of Special Relativity
Time Dilation in Special Relativity
Length Contraction in Special Relativity
The Relativity of Simultaneity
Minkowski Spacetime and Diagrams
Introduction of Generalized Coordinates