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Page 3 + ward ' s science Thermal Energy Transfer Demonstration (continued) Experiment 2 (intermediate)—observing direction of electric current 1. You will need a DC power supply or several batteries connected in series for this procedure. Identify the positive and negative terminals on both the power supply and the Voltage Input/Output plugs and connect them with banana plug jumper wires. 2. Turn the switch to the "Peltier effect" position and turn on the power supply with a 5V configuration. Allow the thermoelectric module to get cold for two minutes. 3. Turn off the power supply and flip the switch on the thermal generator back to "Seebeck effect" 4. Observe which direction the fan turns and compare it to the direction it turned for Experiment 1. If you can't remember, try putting the beaker of hot water back on the thermoelectric module for a few minutes. *A small sticker or a dot made with a marker on one of the fan blades can help with this observation.* Experiment 3 (advanced)—correlating temperature with resulting voltage 1. Begin with the switch in the "Peltier effect" position. 2. Fill the glass beaker with very hot water (80°C) and place it on the thermoelectric module. Allow to equilibrate for at least 1 minute. 3. Observe the fan as it spins. You can calculate the revolutions per minute (rpm) by counting the revolutions in 10s intervals. *A small sticker or a dot made with a marker on one of the fan blades can help with ease and accuracy.* 4. Connect a multimeter to the two 4mm plugs using banana plug jumper wires. Measure the voltage using V or mV by temporarily switching from "Seebeck effect" to "Peltier effect". 5. As the water in the beaker cools, record the fan's speed at various temperatures. Record the voltage produced by the ther- moelectric module for at least 5 different temperatures between 80°C and room temperature. Periodically adding an ice cube with gentle stirring can help speed the cooling process, but be sure to leave extra room in the beaker to accommodate the added volume. 6. Create a graph of temperature vs. voltage using a spreadsheet program or graph paper. Be sure to determine which is the independent and dependent variable. Peltier Effect Experiment 1 (beginner)—comparing temperature changes from different direction of electric current 1. You will need a DC power supply or several batteries connected in series for this procedure. Identify the positive and negative terminals on both the power supply and the Voltage Input/Output plugs and connect them with banana plug jumper wires. 2. Turn the switch to the "Peltier effect" position and turn on the power supply with a 5V configuration. 3. After one minute, gently touch the thermoelectric module and the base of the Thermal Generator. You will notice a temperature difference between the module and the base. Safety For this section of the experiment, the power supply should not be on for more than two minutes. The voltage should not exceed 8V, and the current should not exceed 3A. !