In a flashlight, there is a simple circuit with a switch, a lamp, and a battery linked together by a few short pieces of copper wire. When you turn the switch on, electricity flows around the circuit. If there is a break anywhere in the circuit, electricity cannot flow. If one of the wires is broken, for example, the lamp will not light. This concept can be observed in most electrical devices. Many circuits have a switch so that they can be turned on and off. When the switch is off, it makes a gap in the circuit and the electrons are not able to flow around. When the switch is turned on, it closes the gap and the electricity is able to move and make the device work.
Materials such as copper metal that conduct electricity (allow it to flow freely) are called conductors. Materials that don't allow electricity to pass through them so readily, such as rubber and plastic, are called insulators. Metals like copper have "free" electrons that are not bound tightly to their parent atoms. These electrons flow freely throughout the structure of copper and this is what enables an electric current to flow. In rubber, the electrons are more tightly bound. There are no "free" electrons and, as a result, electricity does not really flow through rubber at all.
Electric Play Dough!
1 cup of water
½ cup of distilled water
3 cups of flour
½ cup of sugar
¼ cup of salt
4 Tbsp. of vegetable oil
3 Tbsp. cream of tartar or 9 Tbsp. of lemon juice
Food coloring (optional)
Medium sized pot
2 spade terminals
Wire stripper/terminal crimper
Battery pack and batteries
First, we’ll need to attach the spade terminals to the leads of the battery pack. Make sure to get an adult to help with this process so no one gets hurt! Slide the wire leads into the openings of the spade terminals. Use the wire stripper/crimping tool to crimp the open end closed and secure the connection.
Next, we need to prepare our conducting dough and insulating dough! Starting with the conducting dough, mix one cup of water, one cup of flour, the salt, cream of tartar/lemon juice, one tablespoon of vegetable oil, and your choice of food coloring in a medium sized pot. While continuously stirring, cook the mixture over medium heat. Soon the dough will become chunky, so keep stirring until the mixture forms a ball in the center of the pot. Carefully remove the ball from the pot and place it onto a lightly floured surface. Use a rolling pin to flatten the dough so it has a chance to cool off a little before you start kneading. Slowly knead the remaining flour into the ball until you’re satisfied with the consistency.
To make a simple series circuit, roll up two pieces of the conductive dough and place a wire into each one; making sure the two pieces of dough do not touch. Then, close the circuit by placing a wire from an LED into each piece of dough. If the LED doesn’t light up, flip it around! LEDs only allow energy to flow in one direction. You’ve just created a series circuit!
Zinn, Kathy. “Small Black Flashlight”. Released into the public domain. Uploaded on 9/12/17 from publicdomainpictures.net
Lewis, Darren. “Kneading Cookie Dough”. Released into the public domain. Uploaded on 9/13/17 from publicdomainpictures.net
Activity example images property of Discovery Express Kids LLC.