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Home / Science projects / Saltwater Circuit
  • Saltwater Circuit

    Saltwater Circuit

    Did you know that you can use salt water to make a light bulb shine? It sounds crazy, but it's true! This is because salt water is a good conductor of electricity.

    Salt molecules are made of sodium ions and chlorine ions. (An ion is an atom that has an electrical charge because it has either gained or lost an electron.) When you put salt in water, the water molecules pull the sodium and chlorine ions apart so they are floating freely. These ions are what carry electricity through water. Watch it work in this project! (Adult supervision recommended.)

    What You Need:

    What You Do:

    1. Wrap two tongue depressors in aluminum foil. These will be your electrodes.

    2. Cut three 6-inch pieces of insulated copper wire and strip a half-inch of insulation off each end.

    3. Connect one end of a wire to the positive terminal of the battery - hold it in place with masking tape. (If you are using a battery cap, connect it to the red wire.) Connect the other end of the wire to the light bulb socket. (Just wrap the wire around the bottom of the bulb, if you don't have a socket. You may have to secure it with tape.)

    4. Take the second piece of wire and connect the light bulb socket with one of the electrodes. Use masking tape to stick the bare end of the wire on the aluminum foil near the top the electrode.

    5. Use the third piece of wire to connect the negative terminal of the battery with the other electrode.

    6. Test out your circuit by touching the two electrodes together. This should complete the circuit and allow electricity to flow from one terminal of the battery to the other, lighting up the light bulb in the process. If the bulb doesn't light up, check your wire connections to make sure they are all secure and then try again.

    Testing the circuit in water

    1. Pour 1 cup water into a cup or beaker. (If you have distilled water, that will work best.)

    2. Put the two electrodes in the cup, but don't let them touch each other. What happens to the light bulb?

    3. Remove the electrodes from the cup and then stir in a teaspoon of salt until it dissolves. Put the electrodes in the salt water without touching them together. Watch the light bulb.

    The light bulb lit up because the sodium and chorine ions conducted the electricity from one electrode to the other. This completed the circuit, causing the light bulb to shine. Try adding more salt and see if the light bulb shines brighter. Use a buzzer instead of a light bulb and see if more or less salt in the water makes the buzzer ring louder or softer.

    Try this solar distillation project to get fresh water out of salt water and then use your saltwater circuit to test the water you distill! Fresh water won't conduct electricity as well as salt water.

    Buy Saltwater Circuit Experiment Kit

    testing for starch kit

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By: lavinia schlatter
Date: Jul 12, 2015

i like it and good for learning

Date: Jul 11, 2015

Can the bult lyt up without bat3…Just using salt water? Pls i need to knw.

By: Troy
Date: Jun 10, 2015

What if we take out the battery and only use the salt and water will it work or not :v

By: Anonymous
Date: Jun 01, 2015

me and my partner are so exited to see how this works !!!!!!! thank you internet \

By: Paul
Date: May 26, 2015

First of all the battery shipped was dead. I am an electrician so my step son wanted to do something with electricity so I thought this would be very easy and fun. First of all there is not enough voltage to push a lamp and buzzer provided to make a substantial change in both light and sound. Second it took a 1/4 cup of salt to make anything happen. Lastly the copper wire provided dissolved quickly due to the fact that it is clearly to small of aguage wire. Don’t buy this product! The idea is great. Go to your hardware store

By: Anonymous
Date: May 09, 2015

Thank you so much! :) This will help me a whole BUNCH with my project

By: Six grade student
Date: May 05, 2015

I really thing this is a great science project for me and my partner I hope we get 1st place =D

By: vidhi
Date: Apr 25, 2015

very useful and nicely explained with good presntation in an organized way.
just that steps could have been shown through diagrams or images.

By: Teacher
Date: Mar 02, 2015

The current of passes through the ions in the salt water. The NaCl does not supply the electricity, it simply allows for conductivity.

By: Comment
Date: Feb 13, 2015

The saltwater does not generate electricity, the battery does. The saltwater directs the electricity to the light bulb, I am not 100% sure, but thats what i think about this.