AP Physics C: Electricity and Magnetism / Unit 13: Electromagnetic Induction
13.2 Electromagnetic Induction
Notes
$$\varepsilon=-\frac{d\Phi_B}{dt}$$
- Lenz's law: the induced current opposes the change in flux.
- Motional emf: $\varepsilon=BLv$.
Practice
A 0.5 m rod moves at 4 m/s through a 0.2 T field (perpendicular). emf:
$BLv$.
$\Phi_B(t)=3t^2$ Wb. emf magnitude at $t=1$ s:
$\displaystyle \frac{d\Phi}{dt}=6t$.
A magnet's north pole is pushed toward a loop. The induced current makes the loop's near face:
Opposes the approach.
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