E is for Electricity: Saltwater Conductivity Experiment and Electric Eels

Monkey has been interested in electricity for some time now.  So when I had the opportunity to participate in the A-Z Science Experiments from Frogs & Snails & Puppy Dog Tail, I made sure to grab “E is for Electricity”!  I also wanted to marry this curiosity with his equally longstanding interest in animals, so I decided to do an experiment related to electric eels.

One of the reasons that the electric eels hunting mechanism (generating electric pulses to stun their prey) works so well is that while they don’t live in saltwater, the waters they live in (the Amazon and Orinoco Rivers in South America) contain enough salt and other minerals to be good conductors.  Pure water is actually a poor conductor of electricity, but throw in a little salt and it’s a different story!

image via electricanimals.wikispaces.com

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Saltwater Conductivity Experiment

An experiment demonstrating saltwater conductivity is easy to do and can work well on varying levels, depending on the interests and ability of your child.  On its most basic level, it’s a “gee whiz!” and “isn’t science fun!” kind of experiment, because it’s quick and you are making something happen, lighting a light bulb or sounding an alarm.  For young kids you can just do the experiment and leave it at that, as a fun science activity.

For older kids, you can delve more into the facts of electricity: the need to close the circuit in order for the electricity to reach the light bulb, the ability of salt to make water a better “conductor” of electricity.  And for even more complexity, you can begin to study about the electrons and how certain molecules make them more likely to want to jump around, creating an electric current.

For this experiment I used Snap Circuits Jr. SC-100, which we purchased recently for Monkey and he just loves.  I basically felt like Super Mom when he opened it because it is super educational but also super fun – Mom for the win!  Although the recommended age is 8 – 15 years old, if you have a younger child that is interested in electronics and/or experiments, I still highly recommend it.  The experiments are easy to do (though the concepts can be explored in great depths) and the equipment is all very safe for little hands to put together.  We sometimes spend long periods of time absorbed in creating circuits but also just pull it off the shelf for a quick experiment when we have a little downtime.  And the snap-together parts also make great building toys 🙂

If you do not have a Snap Circuits Jr. set, you can still do this experiment!  There are plenty of DIY versions out there that are very easy to put together.  But if you do have a set, it will save you a trip to the electronics store.

You Will Need:

Snap Circuits Jr. SC-100 (or see DIY version above)*

Cup of water (distilled, if possible)

Salt

Spoon

*Please note: This is not an authorized use of Snap Circuits Jr., so proceed at your own risk.  I rinsed and dried our jumper cables and was able to reuse them without any trouble, but this is not a guarantee that the same will be true for you.

What to Do:

Build a simple circuit either from the Snap Circuits Jr. handbook or of your own devising.  Make sure it is one that will do something – such as light a bulb, sound an alarm, or turn a motor.  We did it twice – once for a light and once for an alarm.

Remove one of the snap connectors and instead attach two jumper cables (one cable to each side).  Put the other ends of the cables in the cup of water, making sure they do not touch.  The idea is to see whether the water will be able to close the circuit between the two cables, especially once the salt is added.

With plain water – no light!

Try turning on the switch for your circuit.  When this doesn’t work, gradually add more salt and observe the effect.  For us, we could observe how the light got brighter/alarm got louder as we added more salt.  Be sure to keep stirring until the salt is absorbed, otherwise it may just sink to the bottom and lessen the effect.

Discussion:

What happened when we added salt to the water?

How was the circuit closed even though the cables weren’t touching?

What is it about salt that makes it a good conductor?

Would you like to play with an electric eel?  (Nooo!!!)

Additional Resources on Electricity

We are huge fans of the Magic School Bus, so it shouldn’t be a surprise that we have read The Magic School Bus And The Electric Field Trip dozens of times!  I love that it explains electricity in terms that kids can easily understand, without skimping on the details, plus the visuals are great!  Chock full of information, and – as with all the Magic School Bus books – can be enjoyed on a number of levels depending on the age and interest of your child.

We love the DK Eyewitness Books series. They are non-fiction, so for kids that are more seriously into science, but  they work even for young readers as they have lots of great images.  The facts are broken into easily digestible chunks, so they are still fun to read even for those that won’t “get” all of the science quite yet. DK Eyewitness Books: Electricity is no exception. It is a really great book to explore electricity with your little scientist!

Additional Resources on Electronic Eels

Scientific American: How do electric eels generate a voltage and why do they not get shocked in the process?

Ask a Naturalist: How do Electric Eels Generate Electricity?

How Electric Eels Use Shocks to “Remote Control” Other Fish

This post is part of the A-Z Science Experiments series from Frogs and Snails and Puppy Dog Tail.  Be sure to look at all the posts in this series for some great science experiments to do with your kids!

For more fun science activities, check out my Science Experiments for Kids Pinterest board: