# Help me design fourth grade electricity kits--need answer fast! **URL:** \ **Category:** In My Humble Opinion\ **Created:** [January 15, 2021, 1:32pm UTC](https://boards.straightdope.com/t/help-me-design-fourth-grade-electricity-kits-need-answer-fast/930597 "2021-01-15T13:32:54Z")\ **Posts on this page:** 7\ **Page:** 2
**Author:** ![Cheesesteak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cheesesteak/32/3694_2.png) [@Cheesesteak](https://boards.straightdope.com/u/Cheesesteak)\ **Post date:** [January 15, 2021, 4:52pm UTC](https://boards.straightdope.com/t/help-me-design-fourth-grade-electricity-kits-need-answer-fast/930597/21 "2021-01-15T16:52:11Z")
> [@Left\_Hand\_of\_Dorkness](#): > > the sandpaper would be in lieu of my stripping insulation from the ends, right? Exactly, though you need magnet wire more like this [Magnet Wire](https://www.amazon.com/BNTECHGO-AWG-Magnet-Wire-Transformers/dp/B07DYF53ZN/ref=sr_1_1_sspa?dchild=1&keywords=magnet+wire&qid=1610729125&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzVUhWWU5RQzQ5T1EmZW5jcnlwdGVkSWQ9QTAyMjA2MDgxNElIODE1QjVUS0JCJmVuY3J5cHRlZEFkSWQ9QTA0MjQwNzIyR1Y5TzhXUzVSRE82JndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==) The wire I linked has a red enamel coating, not thick insulation and says it’s a 500 foot length… for the nails, you should get two pounds of nails like [these](https://www.homedepot.com/p/Grip-Rite-9-x-3-1-4-in-12-Penny-Hot-Galvanized-Steel-Common-Nails-1-lb-Pack-12HGC1/202308610) The ones you linked are attached to a plastic frame that you’ll need to break apart. They don’t need to be galvanized, but a plain box of nails will be easier to work with. ---
**Author:** ![Left\_Hand\_of\_Dorkness](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/left_hand_of_dorkness/32/7156_2.png) [@Left\_Hand\_of\_Dorkness](https://boards.straightdope.com/u/Left_Hand_of_Dorkness)\ **Post date:** [January 15, 2021, 4:52pm UTC](https://boards.straightdope.com/t/help-me-design-fourth-grade-electricity-kits-need-answer-fast/930597/22 "2021-01-15T16:52:19Z")
> [@Crane](#): > > LHD - something you might try is wrapping a tight coil (strands next to each other) of any light weight (22) wire around something like a water bottle or broom handle. If you remove the coil and sit the coil on a surface and touch the wire ends to a D cell, the individual turns should spring apart. That might be a simpler demonstration. That sounds really cool! If you’re explaining it to a simpleton like me, why would that happen–is it because the wire is all negatively charged and repels itself, or something? ---
**Author:** ![Left\_Hand\_of\_Dorkness](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/left_hand_of_dorkness/32/7156_2.png) [@Left\_Hand\_of\_Dorkness](https://boards.straightdope.com/u/Left_Hand_of_Dorkness)\ **Post date:** [January 15, 2021, 4:55pm UTC](https://boards.straightdope.com/t/help-me-design-fourth-grade-electricity-kits-need-answer-fast/930597/23 "2021-01-15T16:55:43Z")
> [@Cheesesteak](#): > > for the nails, you should get two pounds of nails like [these](https://www.homedepot.com/p/Grip-Rite-9-x-3-1-4-in-12-Penny-Hot-Galvanized-Steel-Common-Nails-1-lb-Pack-12HGC1/202308610) The ones you linked are attached to a plastic frame that you’ll need to break apart. Oof. If they’re easy to get out of the frame, I’ll just do that. Otherwise I’ll sneak into Lowes and buy a couple boxes out of my own money, if it’s worth ten bucks to me not to be snapping nails out of the frame. I think I’m working on my secretary’s grace at this point; although she’s amazingly accommodating, I don’t want to push my luck by changing the order again. ---
**Author:** ![Crane](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crane/32/3495_2.png) [@Crane](https://boards.straightdope.com/u/Crane)\ **Post date:** [January 15, 2021, 4:58pm UTC](https://boards.straightdope.com/t/help-me-design-fourth-grade-electricity-kits-need-answer-fast/930597/24 "2021-01-15T16:58:43Z")
It’s because the current creates a magnetic field around the wire. The polarity works out to oppose so the coils repel each other. With no resistance you should get a massive current pulse and a good magnetic field. I’m not in a position to try it right now but if you play around with it you can make it fit. Like if you suspend the coil between two bottles and click it a couple of times it should bounce back and forth. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [January 15, 2021, 5:01pm UTC](https://boards.straightdope.com/t/help-me-design-fourth-grade-electricity-kits-need-answer-fast/930597/25 "2021-01-15T17:01:15Z")
Use the right-hand rule. The magnetic field the current flowing through the wire generates wraps around the wire in the direction your fingers point if your hand is gripping the wire, and your thumb is pointing in the direction the current is flowing. If the wire is coiled, the axial components of the magnetic fields on different turns are pointing in the same direction, which is a repulsive force. ---
**Author:** ![Crane](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crane/32/3495_2.png) [@Crane](https://boards.straightdope.com/u/Crane)\ **Post date:** [January 15, 2021, 5:23pm UTC](https://boards.straightdope.com/t/help-me-design-fourth-grade-electricity-kits-need-answer-fast/930597/26 "2021-01-15T17:23:44Z")
LHD - With Beowulff’s info you can determine the polarity of the coil. So, you could wind a coil a about an inch in diameter and lay it on a flat surface with a little square of paper over the coil. Place one of your magnets on the paper then pulse the coil. If the polarity of the magnet and the coil are the same the magnet will be thrown off. Otherwise it will press into the paper. That way you can determine and label the polarity of the magnets. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [January 15, 2021, 5:45pm UTC](https://boards.straightdope.com/t/help-me-design-fourth-grade-electricity-kits-need-answer-fast/930597/27 "2021-01-15T17:45:40Z")
I want to correct my answer. I was thinking this over, and realized it couldn’t be correct, and sure enough wikipedia has the right answer: > **[Electromagnet | Lorentz forces](https://en.wikipedia.org/wiki/Electromagnet#Lorentz_forces)** > > In powerful electromagnets, the magnetic field exerts a force on each turn of the windings, due to the Lorentz force > > > > q > > v > > × > > B > > > > {\\displaystyle q\\mathbf {v} \\times \\mathbf {B} } > > acting on the moving charges within the wire. The Lorentz force is perpendicular to both the axis of the wire and the magnetic field. It can be visualized as a pressure between the magnetic field lines, pushing them ap... [Previous page](https://boards.straightdope.com/t/help-me-design-fourth-grade-electricity-kits-need-answer-fast/930597.md?page=1)