Section 29.1 Faraday’s Law
Subsubsection Key Ideas
Definition 29.1.2. Faraday’s Law.
Faraday’s Law says that if the magnetic flux through a surface changes with time, a voltage is induced within the current carrying material:
\begin{equation*}
V_{induced} = - \frac{d\mathit{\Phi}_B}{dt}
\end{equation*}
Representation 29.1.3. Magnetic Induction Tables.
A magnetic induction table is a representation that helps you organize and keep track of the various quantities needed for Faraday’s Law. An example table from the video is reproduced below.
| Quantity | Direction or Sign | Magnitude |
|---|---|---|
| \(\vec{A}\) | Out | \(xy\) |
| \(\vec{B}\) | out | \(B\) |
| \(\Phi_B\) | \(+\) | \(Bxy\) |
| \(\frac{d\Phi_B}{dt}\) | \(-\) | \(Bxv_y\) |
| \(V_{ind}\) | \(+\) | \(Bxv_y\) |
| \(I_{ind}\) | \(ccw\) | \(\frac{Bxv_y}{R}\) |
Subsubsection Activities
Activity 29.1.1. Moving Current Loop.
The current-carrying wire below is being pulled downward, away from the square metal loop.
(a)
As the wire is moving, is there a clockwise current induced around the loop, a counterclockwise current, or no current? Create a magnetic induction table to explain your reasoning.
(b)
Describe a different experiment you could do with the setup in the figure that would result in an induced current in the loop. What direction will the current in the loop be for your experiment, and why?
