A couple of days ago I was searching for experiments that our boys can do with their Lego Mindstorm robot, and I stumbled across an amazing website. It is called TeachEngineering, and has curriculum for K-12 teachers. Some of the lessons are short experiments, but it ranges up to hours long sessions that have PowerPoint presentations. There are easy and hard lessons on a wide variety of subjects.
One of the shorter experiments is to make an electromagnet, and is intended for children in grade 4. There isn’t a large list of items needed, in fact most of the items are real cheap or may be something you have around the house already.
I truncated the lesson quite a bit because I just wanted it to be a fun experiment, and I adjusted the material list somewhat to fit what I had on hand or could buy cheap. I will put the link to the full lesson with a more complete material list and the teaching points at the end of the post.
- 22 gauge wire (I used scrap wire I found at work)
- D Cell batteries
- 4 inch nails (I bought 5 inch at Home Depot for 7 cents each and used some 1.5 inch nails I had on hand)
- Electrical tape
- Paperclips, staples, anything small and metal
We quickly discovered that one of our batteries expired in March of 2011. I have no idea how it ended up in the battery box for so long. It could have been an old used battery that somebody put in the box while getting out a new battery. What I do know is that the old battery didn’t work at all.
To start the experiment, cut a section of wire about 24 inches long for each child (or adult because this is kind of fun). Strip around 1/4 inch of the insulation off of both ends of the wire. Wrap the wire as tightly as possible around the nail leaving 2 inches of each end loose so that it can be taped to the battery. Put the end of the wire near the point of the nail on the positive lead of the battery, and the other end on the negative lead.
If the wires are loosely wrapped then the electromagnet will not work as well. The object is to have the wire wrapped tightly and have the coils as close as possible. Let your children wrap it as they want, but then if they make it loose show them the difference in the magnet based on the wrapping of the wire. The magnet will also work better if the coils are closer to the tip of the nail then the back.
Just so you know, the ends of the battery will get warm to the touch due to the power transference. I wouldn’t leave the wire taped to the battery long term after completing the experiment.
Once you have your magnet set up then you will be able to pick up metal items. This will not be a super powerful magnet, but it should be able to pick up several paperclips and staples. We only had plastic coated paperclips so that might have affected the number we could pick up.
I was even able to pick up one of the 5 inch nails with my electromagnet.
Our boys wanted to also use real magnets to see how those also worked. Our 6 year old put a magnetized rock on his electromagnet and was able to pick up a large number of paperclips.
We also used the smaller nails with the same length of wire. That allowed for many more coils around the nail, and made a better electromagnet.
This was a quick, simple and fun experiment. I was able to teach my boys about magnetism and how an electromagnet works. We were able to discover that tighter coils are better then loose, and more coils worked better then fewer.
This is an easy experiment and shouldn’t require an electrical or electronic background. I would recommend it to anybody that wants to teach their children a simple physical science lesson.
To learn more about the experiment and lesson check out this link.