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Chapter 18. Hands-on Experiment #2: What Conducts Electricity?

Click here for video of experiment

Time: 30 Minutes

Shocking Fact: Why is playdough a good conductor of electricity? There is a lot of salt in playdough. Salt is a chemical that allows electrical current to flow through materials.

Materials:

  • 9V Battery
  • LED lights
  • Playdough and/or Alligator Clips
  • Objects to test: (examples: nickel, wire, chalk, wood, coin, copper, cotton, rubber duck, umbrella, anything you want!)

Experiment:

  1. Setup the circuit from the last experiment. Connect your 9V battery to wires so that an LED bulb lights up.
  2. Open the circuit so there is a gap.
    • If you only want to use playdough and copper wire add a third playdough piece. Connect the wire from the battery to this new piece. Now you will have a gap between the wire connecting the battery and the two playdough pieces connecting the LED light.
    • If you use alligator clips instead, one wire will connect a battery terminal to one LED terminal. Another wire will connect to the other battery terminal and nothing else. The third wire will connect to the other LED terminal and nothing else. You will clip these last two wires to the new objects.
  3. Test each object by placing it in the gap you created in Step 2.
  4. If the lightbulb lights up, then your circuit is full of conductors.
  5. If the lightbulb does not light up, then something in your circuit is stopping the flow of electrons. These materials are called insulators because they protect us from electricity
  6. Record what you see as “Observations”. Use your observation to decide whether the object is a “Conductor” or “Insulator“.
  7. Repeat Step 3 with all your materials while taking good notes of what you observe

Step by Step Demonstration with Explained Vocabulary: Start with an LED light. When you touch the plastic part of the LED light to the playdough nothing will happen. But, if you touch the legs of the LED light to the playdough, the rest of the LED lights will shine. Why? The legs of the LED lights are made from metal. Metal is a good conductor of electricity. Conductors are materials that allow the flow of electrons freely. A good conductor transfers electrons well. The reason why the plastic part of the LED light does not cause the other lights to shine, because plastic is an insulator. Insulators are materials that electrons do not flow freely, but instead, are fixed in one place. A good insulator does not transfer electrons well. 

If you want to share your work, you can upload a picture, video, or PDF file below!

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Video: https://www.youtube.com/watch?v=QvsyDc8Bbzo