Unit III On-a-Page

17 Unit III On-a-Page

This chapter very strongly follows the ideas of a few distinct discussed in Unit I On-a-Page.

All charges generate electric fields $\vec{E}$ (units N/C orV/m)
For a point charge $\vert \vec{E} \vert = \frac{1}{4 \pi \varepsilon_0} \frac{q}{r^2}$
Point away from positive, towards negative
These are real and exist regardless if something is there to feel or not!
Put a charge in an electric field ⇒ it will feel a force $\vec {F } =q \vec {E}$
Can also think in terms of energy: All charges generate electric potentials $V$ (units Volts)
For a point charge $V = \frac{1}{4 \pi \varepsilon_0} \frac{q}{r}$
Exists if something is there to feel or not!
Put a charge in a potential it has a potential energy $U = qV$
Electric potentials and electric fields are two sides of the same coin
Just like in P131: Can think of forces or energy
$\vec{E}$ points ‘down the potential hill’
$\vec{E} = - \frac{\Delta V} {\Delta x}$

Icon for the Creative Commons Attribution 4.0 International License

Physics 132: What is an Electron? What is Light? 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.