AP Physics C: Electricity and Magnetism / Unit 8: Electric Charges, Fields, and Gauss's Law
8.1 Electric Charge and Electric Force
Notes
$$\vec F=\frac{1}{4\pi\varepsilon_0}\frac{q_1q_2}{r^2}\hat r$$
- Forces from several charges add as vectors (superposition).
Practice
Two charges are 3 times farther apart. The force:
Inverse square.
$+q$ at $x=0$ and $+q$ at $x=2$ m. The net force on a test charge at $x=1$ m:
Equal and opposite pushes.
$\displaystyle \frac{1}{4\pi\varepsilon_0}$ is about:
Coulomb's constant.
Ready for more? Take the Unit 8 test.