Tuesday, July 22, 2008

Current carrying wire

During a recent long and particularly boring meeting I was sitting next to a laptop computer which was plugged in to a wall outlet. I used my magnetic sense to explore power supply, which emitted a now familiar buzz from the small transformer inside it. I was quite surprised to also feel a sensation from the power cable as well, a faint vibration but definitely there.

When current flows through a straight conductor, there is a magnetic field encircling it. In the case of a DC current the field is stable and the direction can be determined using the right hand rule.
An illustration of a DC current carrying wire's magnetic field.


AC current, however, produces an oscillating field which can be picked up with the implant. Having explored several power cords, it appears that low current devices (like light bulbs) don't draw enough current to be detectable. Only higher current draw devices produce the faint buzzing sensation. Also, only the hot wire will yield a sensation, as the neutral wire normally carries no current. The cable type itself plays a large part in detectability too. Shielded cable (predictably) is far less likely to produce a detectable field, as is cable that is enclosed in metal conduit.

Pretty cool, nonetheless.

5 comments:

Toby said...

This blog is awesome, thanks so much for putting it up! As it stands right now I think I'm going to order a stir rod and have it implanted. I'll take your advice on appropriate placement, but I'd be curious to know why you didn't select the portion of the finger one joint down from the tip. I think I'll re-read your posts to see if there's an explanation I missed.

Anyway, thanks again.

Toby

Nate said...

I chose the tip of the finger because it has the highest density of nerves. The second joint would be a good choice though, as it leaves the implant less vulnerable. I would be interested in the intensity of sensations in this region. I have quite a surplus of the magnets if you would like to save the trouble of ordering one.

Toby said...
This comment has been removed by a blog administrator.
Nate said...

I deleted your last comment, for privacy concerns. If you would like to contact me by email it should be accessible via my profile. :)

michaelangel0 said...

"only the hot wire produced a sensation as the neutral wire carries no current"
I may be mistaken, but neither wire inherently carries any current.
The hot wire is at a voltage that changes over time, oscillating at the country's electrical supply voltage, and the neutral wire is stable at 0V. Alternative current flows through both wires if a non-infinite impedance load connects the two.

Hope this helps.