Unit V On-a-Page

Only moving charges (i.e., currents) generate and feel magnetic fields
The field is “real” and the key object (just like for electricity)
Moving charges make fields, which can then exert forces on other moving charges
Use your right hand: thumb in current ( $\vec{I}$ or $q \vec {v}$ ), fingers in $\vec{B}$
For the direction of a magnetic field, fingers curl in direction of $\vec{B}$

Figure 1.
$\vert \vec{B} \vert = \frac{I \mu_0}{2 \pi r}$
$\mu_0$ is another universal constant like $h$ , $c$ , $\varepsilon_0$ , and $\mu_0 = 4 \pi \times 10^{-7} \frac{N} {A^2}$
For the force, palm “pushes” in the direction of $\vec{F}$

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Physics 132: What is an Electron? What is Light? Copyright © 2020 by Roger Hinrichs; Paul Peter Urone; Paul Flowers; Edward J. Neth; William R. Robinson; Klaus Theopold; Richard Langley; Julianne Zedalis; John Eggebrecht; and E.F. Redish is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.