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Page 2 + ward ' s science Thermal Energy Transfer Demonstration (continued) When heat is applied to one end of a conductor and the other is cooled, the tempera- ture difference causes the electrons present in the metal flow from the hot end to the cold end. Figure 1. This happens because electrons move to where energy, in this case heat, is lower. If two distinct metals are connected through an electrical circuit, the charge carriers have different energy levels in each material. As a result, a voltage differ- ence is generated between the hot and cold ends of the conductors and direct current flows through the circuit. The magnitude of the voltage depends on the temperature difference, the properties of the materials, and the junction configuration. Figure 2. Peltier Effect This phenomenon was named after the French physicist Jean Charles Peltier who discovered it in 1834. During Peltier's investigations into the relationship between electricity and heat, he noticed that passing current through certain metal junctions resulted in one side heating up while the other side cooled down. The Peltier effect is the inverse phenomenon of the Seebeck effect. While the Seebeck effect involves the generation of a voltage difference due to a temperature gradient, the Peltier effect causes a temperature difference when an electric current passes through a circuit of two different conductors. There are many applications for the Seebeck and Peltier effects in different fields. They are applied in thermoelectric power generation, waste heat harvesting, and thermocouple temperature sensing. Thermoelectric coolers and other Peltier effect- based devices are used in solid-state cooling of electronics, medical equipment, and food preservation. Objective: Qualitatively observe several energy transformations using a thermoelectric module. Quantitatively explore the relationship between temperature and electric potential in thermoelectric materials using both the Seebeck effect and the Peltier effect. By varying temperature differentials and electrical inputs, analyze the behavior of thermoelectric generators and their potential applications in energy conversion and thermal management systems. Materials: In addition to the GSC Thermal Generator (470356-482), you will also need a thermometer, stopwatch, low voltage DC power supply or batteries, digital multimeter, and a heat-resistant beaker to complete the experiment. Method: Seebeck Effect Experiment 1 (beginner)—correlating temperature with electric energy produced 1. Make sure the switch is in the "Peltier effect" position. Heat water until it reaches 80°C and fill the glass beaker, then place it on top of the white thermoelectric module. 2. After 30 seconds, flip the switch to the "Seebeck Effect" position and observe what happens with the fan. 3. Carefully take the beaker away from the module after a minute has passed. You'll notice the fan will stop rotating after a few seconds, measure the time it takes to stop completely from the moment you remove the beaker. 4. Maintaining the water's temperature at 80°C, repeat Step 2 with different wait periods (5s and 45s) before flipping the switch. Observe how the fan behaves differently compared to the 30s wait period. 5. Repeat steps 1–3 changing the water's temperature to 50°C, 60°C, 70°C, and 90°C, then write down the results. Note: Between each take wait until the thermoelectric module has cooled down completely. Figure 1: Voltage is created by temperature differential. Figure 2: Current flows due to difference in charge separation between materials.