AP Physics 2 / Unit 12: Magnetism and Electromagnetism
12.3 Magnetism and Current-Carrying Wires
Notes
- A wire in a field: $F=ILB\sin\theta$.
- A long straight wire makes a circular field: $\displaystyle B=\frac{\mu_0I}{2\pi r}$.
- Parallel currents attract; opposite currents repel.
Practice
Two parallel wires carry current in the same direction. They:
Same direction attracts.
Doubling the distance from a long wire makes $B$:
$\displaystyle B\propto\frac{1}{r}$.
A 2 m wire with 3 A in a 0.5 T field (perpendicular) feels:
$ILB$.
Ready for more? Take the Unit 12 test.