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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: Jonathan addo
    Date: Aug 06, 2017

    Please after collecting the two wires to bulb.in 2minute time
    The salt loses it power again.please if there is any solution to that
    Let me know

    By: Nelson Soto
    Date: Aug 05, 2017

    Very disappointed, didn’t work, very briefly in some of the groups that was making the experiment, then I did it myself at home double check the procedure, work once very briefly as well. I don’t think that we will spend any more money through Home Sciece Tools.

    [HST adds: Sorry to hear it did’n't work for you! Customer Service has tried to reach you regarding your order. Remember that all our products are backed by our 90-day, money-back, satisfaction guarantee!]

    By: April
    Date: Mar 03, 2017

    Very disappointed. We got the bulb to light up once using battery only. After that the wire fell off the battery. It is very, very hard to twist tiny wires around the top of the battery. Not a good experiment. Bought a $9 potato clock electricity kit and it works much better. Personally I spend $100s of dollars at HomeScience Tools through our school, I will be rethinking this.

    By: Regina Lambright
    Date: Feb 16, 2017

    The bulbs seemed to blow almost as soon as we got them connected.  I want to make this project work for my students, but with the bulb I from the store it is not seeming to work.

    By: Mia
    Date: Mar 16, 2016

    Can you use this without the battery? That would be great to know.

    By: Ej
    Date: Feb 22, 2016

    You can actually just use some nails, hot water, and if you’d like a device that will tell you how much energy is being let off! Nothing else needed!

    By: 6th Grade Student
    Date: Jan 23, 2016

    The bulb will just light up with the battery. It doesn’t need the salt water.
    :(  :(  :(  :(  :(

    By: Sam
    Date: Dec 13, 2015

    is there a way to add a multimeter to read the milliamps and not use lightbulbs?

    By: fesa
    Date: Nov 25, 2015

    Troy that is not true. Some electricity will be conducted but only noticeable at the 2000 level on a multi-meter

    By: JMyke
    Date: Nov 25, 2015

    You can also use a cup instead of the popsicle sticks and it works and its less materials and less work