Lesson at a glance
Students will learn how thermal energy transforms to mechanical energy, and how mechanical energy transforms to electrical energy. They’ll generate electrical energy by building a small-scale, functioning wind turbine, and will make and test predictions about what turbine set ups will create the most electrical energy.
Wind is caused by differences in pressure created by the uneven heating of Earth’s surface by the sun. Radiation from the sun causes land to gain thermal energy. The air above the land also gains thermal energy and expands, becoming less dense and rising.
This movement causes an area of low pressure at the surface, creating a vaccuum that draws air in. Cooler, denser air flows toward the low pressure area at the surface to fill in the space left by the risen, heated air. This creates a convection current and thermal energy is transformed into kinetic mechanical energy in the form of moving air or wind.
A wind turbine transforms the mechanical energy of wind into electrical energy. A turbine takes the kinetic energy of a moving fluid, air in this case, and converts it to a rotary motion. As wind moves past the blades of a wind turbine, it moves or rotates the blades. These blades turn a generator. A generator works as an inverse of an electric motor; instead of aplying electrical energy to turn it and create mechanical energy, it uses mechanical energy to turn and create electrical energy. Generators spin coiled wire around magnets to create an electrical current.
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