Electricity Adventure: Illuminating Science with a Saltwater Circuit

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Building a saltwater circuit with your preschooler is a fantastic way to introduce them to the wonders of science and electricity!

This experiment walks through building a simple circuit using saltwater (which happens to be conductive!). It combines the science of saltwater and the technology of a circuit in one fun experiment.

Who knows, this simple saltwater circuit might be the spark that ignites a lifelong passion for science and engineering in your little one. Happy experimenting!

Build a saltwater circuit with LED battery and salt water technology experiment for kids

How to make the Electricity Adventure Saltwater Circuit technology experiment

Supplies you will need

For this experiment, you will need the following:

Supplies needed for the Electricity Adventure Saltwater Circuit technology experiment

Before you start

Please watch your child around electronics and scissors in this experiment.

Instructions

Here is how to do this experiment with your toddler:

Step 1: Assembling the saltwater solution

Creating the saltwater solution

First up, we’re going to make our saltwater solution for the experiment. Sprinkle some salt into the container with water and mix it until dissolved.

We just created an ionic bond!

Here’s a little science behind why salt water is conductive (and why salt by itself isn’t): when the salt (sodium chloride) dissolves in the water, the chlorine and sodium atoms separate because of the water molecules.

Those chlorine and sodium atoms move around the liquid as both positively and negatively charged ions, and that separation of charge allows our salt water to conduct electricity!

Here’s a good article diving further into how salt water is conductive.

Step 2: Connecting the battery

Connecting alligator clips to the battery terminals

First, we are going to use two alligator clips to connect to the positive and negative terminals of the battery.

I decided to use black for the negative and red for the positive since those are the typical color associations. It also helps me keep track of my positive and negative flows of current!

Step 3: Connecting the LED to the alligator clips

Connecting alligator clips to the LED

Next up, we are going to use our existing positive current alligator clip (my red alligator clip from the last step) and a new alligator clip for the negative current.

The positive current will run to the positive leg of the LED (the anode, or the longer of the two legs) and the negative current will run to the negative leg of the LED (the cathode, or the shorter of the two legs).

Here’s a picture showing the anode and cathode that I’m using from our conductive dough circuit experiment:

Showing the two legs of the LED

So, for our experiment, we want to use the alligator clip that is connected to the positive terminal on our 9-volt battery to the anode of our LED. Then, use a new alligator clip (I chose black because it’s negative current) to connect to the cathode.

Step 4: Connect electrical wires

Next up, we’re going to connect an electrical wire to the alligator clip that is coming from the negative terminal of the battery. Take a look at your electrical wires and ensure that the ends are exposed. You can see it in the photo below that about half an inch of the electrical wire has been exposed using scissors.

Then, connect another electrical wire to the alligator clip coming from the cathode (shorter leg) of the LED.

We’re about to close our circuit!

In case any of that is hard to visualize, here’s an annotated photo:

Annotated version of the electrical wires connected to the alligator clips

Step 5: Close the circuit!

Complete circuit with LED lit up

We’re closing our circuit in this step!

Again here, we want to make sure both ends of each electrical wire are exposed. When we dip the electrical wire in the saltwater solution, we want to make sure the end is exposed so we can complete the circuit.

To close the circuit, dip the exposed ends of the electrical wires into the saltwater solution.

Your LED will light up!

Close-up photo of the LED being lit up

Step 6: Experimenting with the circuit

Now comes the fun part—experimenting with the saltwater circuit! Here are some additional activities to explore:

  1. Changing the brightness: Gradually add more salt to the water and observe how it affects the brightness of the LED. More salt increases the conductivity, causing the LED to shine brighter.
  2. Exploring different materials: Substitute the saltwater with other solutions like sugarwater or vinegar and see how they impact the circuit. Note that not all liquids conduct electricity, so it’s an excellent opportunity to discuss the concept of conductors and insulators.
  3. Creating a circuit with multiple LEDs: Using more copper wire, LEDs, and a battery with a higher voltage, experiment with building more complex circuits, such as series and parallel connections, to light multiple LEDs simultaneously.

The technology behind the Electricity Adventure Saltwater Circuit technology experiment

This experiment teaches:

  • Introduction to electricity
  • Conductors and insulators
  • Curiosity and exploration

How it works

The saltwater circuit experiment works by creating a circuit with a battery, LED, and salt water, and connecting them with electrical wires and alligator clips.

When a 9-volt battery is connected to the circuit, we are introducing an electric current to the circuit. As current flows to the salt water, the presence of the sodium and chlorine atoms allows the electricity to continue to flow through the water.

As a result, the LED lights up!

Introduction to electricity

The saltwater circuit experiment introduces kids to the concept of electricity in a simple and tangible way.

It’s an excellent way to show how a circuit works to light up the LED. If any of the components are removed from the circuit, it may not work as well as intended.

Conductors and insulators

Through this experiment, kids can grasp the distinction between conductors and insulators.

They discover that salt water, as a conductor, allows electricity to flow, while other materials might not (like sugar water).

This lesson helps them understand why certain substances are used to conduct electricity in everyday devices.

Curiosity and exploration

Engaging in hands-on activities like building a saltwater circuit sparks curiosity and encourages kids to explore and ask questions.

They are able to play with the circuit to learn what each piece does, change out materials to see how it affects the circuit, and if they’re really interested in circuits and electricity, could even open the door to talk about electricity in everyday household objects!

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