Does coil winding impact current direction? (Lenz Law)

Question

When a magnet is moving toward a wire loop north-side first, the current goes counterclockwise according to the magnet's perspective, as shown in the image below from Wikipedia. Now, consider a solenoid where each loop is wound so that travelling counterclockwise (again, as seen from the magnet) takes you toward the magnet. If the magnet were to be moved toward this solenoid like it was moved toward the wire loop, the current would still travel counterclockwise, which, as we just stated, means that the current will also travel toward the magnet.

What would happen if the solenoid was wound the other way, i.e. so that travelling counterclockwise takes you away from the magnet? Would the current travel away from the magnet if we moved the magnet toward the solenoid as we did before? I've asked my physics teacher and googled a ton of stuff related to Lenz Law but haven't found an explanation.

Thanks!

Answer 1

What would happen if the solenoid was wound the other way

In the second picture, I've put your first picture winding (now in red) in series with the winding from the 2nd picture (black). There is no discrepancy here at all. There is no change in the direction of currents and no cancellation and the universe remains intact.

In fact this is how you would wind an inductor or coil in two layers. Current remains in the anti-clockwise direction when viewed from the axis of the magnet (as the magnet is travelling towards the coil).

Answer 2

Only current I changes the magnetic field B. The arrows in your first image indicate that current is flowing from left to right while in the second image current is flowing from right to left that's why we will have two different magnetic fields for the two currents.

A magnetic field is a 3d vector:

$$ \overrightarrow{B} = (x_0, y_0, z_0). $$

The magnetic flux through a surface \$ {\rm d}A \$ is:

$$ \Phi = \int \int \overrightarrow{B} \cdot \overrightarrow {{\rm d}A}. $$

Faraday's law of magnetic induction tells us that

$$ V = -k \frac{{\rm d}\Phi}{{\rm d}x}. $$

The - sign is required for conservation of energy if it wasn't - energy isn’t conserved.