Electrical – Artful Coils: How will changing the shape of coiled wire change the resistance

"Vape Mods" are a type of atomizer used in e-cigarets. These "mods" can be built basically from scratch. The simplest mods consist of little more than a battery and a coil shorted over the battery drenched in a vegetable glycerin(VG) and propylene glycol (PG) mixture soaked into an organic cotton or silica wick. The circuit is completed when the button is pressed and the coil (often made of nichrome wire) atomizes the PG/VG mixture into vapor.

Vaping has created a diverse DIY community, and intense interest in Ohm's law among many people who might not have other wised been at all curious about electronics.

Here is an Ohm meter designed especially for vaping atomizers.

Coils come in many shapes and designs. The shape, length and thickness of the nichrome wire changes the resistance of the atomizer. The shape of the coil also has an impact on wicking and vaporizing the PG/VG mixture. The coils are often hand-made and designs are shared over the internet.

Here a is guide showing the basic relationship between coil diameter, wire length, wire gauge and resistance.

But what about something like this?

There are effectually two coils in parallel and one of them is made of smaller coils.

In theory, any resistance can be reached by having a wire with no coils of the correct length. I would not be effective for vaping, but as I understand it, the only important variables when calculating resistance are the diameter and length of the wire and how many other wires are in parallel or series.

But, is that really the whole story? Some of the time a coil touches itself. Wouldn't that make it, effectively, like a lower gauge wire?

And these coils are effectively inductors. Will that have any impact? I suspect the inductance is too low for this to matter, but it's something that I've always wondered.