Electron Flow

Learning Objectives

In this activity students will become familiar with the components of an electrical circuit by modeling a circuit with the use of a deck of playing cards.

Associated Curriculum Topic

Electricity and Electrical Devices

Materials

• Deck of playing cards
• Three paper/cardboard signs on string to denote each of the switch, bulb and battery (the sign for the switch should be double-sided: “switch on” written on one side and “switch off” written on the other)

Introduction/Motivation

A circuit is the complete path of electrical energy. In every circuit we need a source of energy; in most simple circuits this is provided by a battery. When the electrons flow through the battery they gain energy, but when they flow through the bulb they lose energy as it is converted to other forms like light and heat. The current, made up of electrons, flows through the battery, the light bulb and the wires. If there is a break in the path, the electrons can not flow and the bulb will go out. A switch in a circuit acts to control the flow: when the switch is open, the circuit is incomplete and no current flows. When the switch is closed, the circuit is complete and current flows again. By opening and closing the switch, we are controlling whether the light bulb is on or off based on the flow of electrons.

Procedure

• make a large circle with the students in your class
• decide upon three students in the class to act as one of the following three components:
  - A switch
  - A light bulb
  - A battery
  Note: the remainder of the class will act like wires connecting the components. Give each of the components their sign to indicate their function. It doesn’t matter where in the circle the various components are; the circuit will function the same regardless.
• ask the switch to step out of the circle and turn their sign to “switch off” before starting
• ask the battery to indicate which hand is their negative terminal. This will dictate the flow of current.
• each student gets a playing card, including the battery, the light bulb and the switch
• once the students are ready to begin, ask the switch to change his/her sign and step back into the circle. The circuit is now complete and electrons have a complete path for flow. Each student should pass his/her card to the person beside them. The side they pass to should be the same side as that chosen by the battery as his/her negative terminal.
• as the cards (electrons) are circulating, the bulb is “glowing” (singing, humming, wiggling on the spot, smiling broadly … allow students to improvise this!)
• have the switch turn his/her sign to off and step out of the circle. Now that the circuit is incomplete, students must stop passing cards, and the bulb stops “glowing”.
• when the switch turns his/her sign again to on and returns to the circle, the current resumes and the bulb glows again.
• re-assign roles several times during the activity. See if the students have ideas of other items that could use the flow of energy just like the bulb.

Investigating Questions

Name Game: Have the students name the following parts of their circuit by asking the students: Which part of our circuit was ________?

• The current? (Answer: The cards/electrons formed the current moving through the circuit.)
• The resistance? (Answer: There were several resistances, or resistors. The light bulb created resistance by changing the electrical energy into light energy. The switch was a resistance since it could open to stop the current from flowing. And, the students, representing the wire, were also resistors, although wires provide much less resistance to the circuit than the bulb.)
• Open circuit? (Answer: The circuit was open when the switch was "off," the circle was broken, and the electrons stopped flowing.)
• Closed circuit? (Answer: The circuit was closed when the switch was "on, the circle was complete, and the electrons were flowing around the circuit.)

Adapted from Teach Engineering