A school of fish: electricity

Showing posts with label electricity. Show all posts

Monday, May 24, 2021

Electricity and Magnetism Unit Study (II)

I decided it was time for another Electricity Unit mostly because Teddy had been asking me tons of questions about electricity, and has also been very fascinated with/scared of (those two things often go together) lightning lately. It was funny to realize that the girls haven't learned any of this either, since we last did this unit in 2014. Malachi claims to remember everything, but he was only 6, so I'm not sure I believe him. But he was like Teddy back then—very curious and inquisitive and serious about learning, and a FULL participant in everything we did, so maybe he does remember!

I also feel like I did a more complete job on this unit the previous time through. Abe and Seb both understood a lot about electricity already, and helped me figure out a lot of things! And they were very excited and eager to do all the activities, which is always helpful. I was surprised how much the girls liked working with the snap circuits, etc., too this time—but they weren't AS fanatical about it as the boys were back then. I think this subject was just of particular interest of both of those older boys!

Here is the pinterest board from 2014, with perhaps a few pins added this time: https://www.pinterest.com/marilynnielson/electricity-and-magnetism-homeschool-unit/

A good place to start when talking about electricity is with the structure of the atom, and by explaining how ions work. Here are the children playing the "pass the electron" game (we do something similar to this one: https://www.nationalgeographic.org/activity/circuits-friends/print/)

Here are some explanatory videos we watched:

Ions: https://www.youtube.com/watch?v=bnudaqeTyto
Atoms: https://www.generationgenius.com/videolessons/atoms-and-molecules-video-for-kids/

More activities we did last time: https://nielsonschool.blogspot.com/2014/04/electric-current-conductors-and.html

Luckily, we still had most of our electricity and magnetism supplies from last time. They're great to have around for homeschool in general. Here's the list of supplies I made last time, and links to where to get things. Annoyingly, some links are broken, but a google search for that item usually yields lots of choices.

Here are some other videos we used:

Intro to circuits (beware annoying narrators): https://www.generationgenius.com/videolessons/electricity-and-circuits-video-for-kids/?gclid=CjwKCAjwhMmEBhBwEiwAXwFoEW1-Ub4d055l4boFmt-kvSXoab4mptqupBftaK02wHecFK9qWMYfRhoC76IQAvD_BwE

Make sparks http://www.learnplayimagine.com/2013/04/how-to-make-lightning.html

Slow motion lightning strikes: https://www.youtube.com/watch?v=KO3H285CFRo

The electric eel https://www.youtube.com/watch?v=z0M7_HPSi14

Make a telegraph machine https://www.energizer.com/science-center/how-to-make-a-simple-telegraph-set

Virtual coal power plant tour https://www.youtube.com/watch?v=2IKECt4Y3RI
Nuclear power plant tour: https://www.youtube.com/watch?v=_AdA5d_8Hm0
Hydroelectric: https://www.youtube.com/watch?v=Ki8kSB1ThJQ
Substation: https://www.youtube.com/watch?v=7Q-aVBv7PWM

You can learn a lot just by playing around with making your own circuits. The children had a lot of fun doing that in an open-ended way with all the supplies we had. Snap circuits are, of course, fun too, but they don't have the immediacy of a real circuit with a bulb and battery you add in yourself.

More ideas for circuit exploration: https://nielsonschool.blogspot.com/2014/04/simple-foil-circuits-series-and.html

And some further study of switches and resistors: https://nielsonschool.blogspot.com/2014/04/resistors-and-switches.html. That link includes an explanation of three-way switches, which I had forgotten and had to relearn this time. Here's Daisy giving another explanation of it:

And a few more resources:

• Make a three-way switch https://www.youtube.com/watch?v=6_TpKdYeQaU

• Make paper circuits with pencil https://www.youtube.com/watch?v=BwKQ9Idq9FM
• Make foil circuits https://www.youtube.com/watch?app=desktop&v=qJDgl9eVpy8

Making a homemade light bulb is always fun! It's so dramatic when it burns out.

Instructions here: https://nielsonschool.blogspot.com/2014/04/homemade-light-bulb.html

Or you can refer to these pictoral instructions: https://www.wikihow.com/Make-a-Light-Bulb

We talked about batteries and made a voltaic pile. (You can also dissect a battery—see that same post)

Friday, May 2, 2014

Electroplating: Copper-plating Nails and Cleaning Pennies

We talked about electrolysis and electroplating, and we wanted to try zinc-plating a penny as described here, here, and here. The hard part is getting the zinc for dissolving in your solution. We tried using the zinc casing from our dissected battery, but for some reason that didn't work. We could have tried to track down some hydrochloric acid and copper sulfate to use instead, but that seemed like too much trouble when we could demonstrate the concept another way.

So, first we cleaned pennies to show how copper oxide (that greenish stuff, like rust but called "verdigris," that forms on old copper) dissolves in a vinegar and salt solution. (Instructions are here.) You can clean pennies by dipping them in the solution, like this:

A half-dipped penny---you can see the difference between cleaned and uncleaned!

If you leave the pennies soaking in this solution for awhile, they get all shiny and clean. Then, if you remove them from the solution and DON'T rinse them with water, the copper quickly begins to oxidize again and the greenish-blue verdigris starts to form. You can see it clearly on these pennies above. Interestingly, this is the same chemical reaction that forms malachite and azurite!

After you've soaked the pennies, many of the copper ions have left the outside of the pennies and have become suspended in your solution. So, once the pennies are out, you can put in some small steel nails or paper clips. After awhile, the suspended copper ions (positively charged) will attach themselves to the (now negatively charged, from sitting in the solution and giving up some of their positive ions) steel nails. If you leave them in long enough, your steel nails and paper clips will end up plated with a thin layer of copper! It looks really pretty.

(unplated paper clip on the left, for comparison)

The longer you leave them in, the brighter and more noticeable the copper plating will become! These were left in for a few days.

This isn't truly electroplating, because there was no electric current in the solution to help facilitate the process. But you can see how electroplating works based on this---the current just pushes the ions off the anode and makes the object to be plated into a cathode, so it will attract those ions. Very cool!

Thursday, May 1, 2014

Electromagnets and Motors

It's pretty easy to make a simple motor. We got excellent instructions here. As you can see, it's just made of a battery, two safety pins (which act like wires to conduct electricity from the battery to the magnet wire, but serve the added purpose of having holes for the wire to spin through!), a coil of magnet wire, and a magnet. We used clay to hold the battery in place.

I would add, to the instructions linked above, that you should make your coil of wire by wrapping it around a size _C_ battery (not D)---otherwise it will be too large in diameter to turn freely.

You also need to make sure to only scrape off the wire coating on half of the wire's diameter. In other words, the copper wire that goes through the safety pins will only be in contact with electricity for half the time--as it spins, the coating and the wire itself will take turns contacting the safety pins. This is essentially your commutator, allowing the direct current of the battery to alternate its path into the coil and thus keep the motor spinning.

Once you get it going, it should spin on its own for quite a while, and you can stop or slow it by bringing magnets close to the coil. It's really fun to play with.

We also made an electromagnet that could pick up paper clips when the current was flowing, but not when the circuit was broken.

More motor and generator stuff:

This page on motors, with animations, is really great

I think I linked this elsewhere, but we liked this information on AC vs DC motors

And this is a good video on the induction motor.

This generator project looked pretty fun. (Here is our previous, ill-fated attempt at a hydropowered generator--maybe taking out the hydropower component would make things simpler and less liked to go wrong!)

Here are Abe's and Seb's diagrams of how motors/generators work:

And the one we made all together

Monday, April 28, 2014

Magnet Play: 2-D Magnetic Fields, Magnetic Art, Making a Compass

Making your own compass is fun and easy---you just need to magnetize a needle. Do this by stroking a magnet in the same direction 30 or 40 times along the shaft of a needle. Poke the needle through a square of tissue paper (to give it more surface area, so it will float---it needs to be able to turn freely, with little resistance or friction) and float it on water. It will turn until it's pointing north. You can check it with an already-made compass, or by bringing magnets close to it to make it turn around.

You can also make a visible magnetic field by putting a magnet underneath a piece of paper and sprinkling iron filings on top. These are so beautiful!

And there are lots of other fun ways to play with magnets too.

We also made magnetic art, with moving parts controlled by magnets. The children drew a picture that needed motion (Seb and Abe made trains, Ky made a sun orbiting another sun) and attached a paper clip to the back of the part that needed to move. Then they could move it around "magically" by using a magnet behind the picture.

Tuesday, April 22, 2014

Batteries--making a voltaic pile and dissecting a battery

Dissecting a battery is one of those things I've always kind of wanted to do but didn't know I was allowed to! :) I got the idea from this site, which gives step-by-step instructions. Make sure you use only the carbon-zinc batteries, as alkaline batteries may have dangerous acids in them that can burn you!

We talked about cells vs batteries. The batteries we dissected here are technically cells—you'd need two or more to make an actual battery. A 9V battery, on the other hand, actually is a battery—you can see a picture of the cells inside it, here.

Here is our battery, all taken apart. You can see the blue plastic casing, the two round electrodes (the ends of the battery), the carbon rod (covered with black stuff which is manganese-oxide, the electrolyte), and the zinc casing (the thin metal tube that goes around it all).

We also made a Voltaic Pile, or a homemade battery with dimes and pennies. You sandwich them with paper towel pieces soaked in lemon juice and salt, and that's enough to generate a small current. We got our instructions from a book, but here are some similar instructions online. It's a pretty simple activity.

Here you see that no current is going through (our circuit isn't complete)

Here is the current generated by our tiny battery

And here is the measurement when the current is going through Sebby's body instead of the wire---the resistance has increased (Sebby isn't as good of a conductor as a wire is) so there is less electricity getting through.

More battery activities:

There are a million descriptions online of how to make a lemon battery; here's one.

This is a similar project to ours for a homemade battery, but it involves sanding down pennies which seemed more complicated.

This is a cool site; it has diagrams of what's inside various types of batteries (in case you are curious about the ones you can't dissect yourself!) :)

Video about how batteries work

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