# Does coil winding impact current direction? (Lenz Law)

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!

• I cannot figure out in your words what you are proposing to change or how your new experiment looks. Be clear; draw a picture. Commented Mar 27, 2022 at 18:08
• I've now added a picture of the experiment. Does this make things more clear? Commented Mar 27, 2022 at 18:26
• Does this help? physics.stackexchange.com/questions/170091/… Commented Mar 27, 2022 at 18:49
• @enhzflep I think the question you linked further exemplifies my problem. We know that the magnet forces the current counterclockwise, but can we determine if the current moves toward the magnet or away from it without knowing how the solenoid is wound? If we say that the counterclockwise movement is on the xy-plane I'm asking for the movement along the z-axis (from one end of the solenoid to the other). Commented Mar 27, 2022 at 19:08
• "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?" - Yes. Do you have a problem with that? Commented Mar 27, 2022 at 20:27

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).

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.

• I understand your reasoning, but the problem is that the magnetic fields should be the same (see the image from Wikipedia, top row, second from the left). If they weren't the same, one of the ways of winding would result in the magnet getting pulled toward the solenoid faster and creating an even stronger magnetic field which would break the conservation of energy. Commented Mar 27, 2022 at 18:46
• @Kaputsky I will edit. Commented Mar 27, 2022 at 19:12
• Thanks for the edit! I still have a problem in the case of the bottom picture in my diagram. If the wire is wound like that, how can the current both go counterclockwise and follow Faraday's law of magnetic induction? It seems like there is no way for it to follow that law without travelling clockwise. Commented Mar 27, 2022 at 19:53
• @Kaputsky why there doesnt seem a way to follow Farday's law of induction with travelling clockwise? Commented Mar 27, 2022 at 20:05