Science 9: Unit D: Topic 4 Notes The Energy Connection What exactly is energy? Energy – is the ability to do work. Much of our energy is supplied by current electricity. This electrical energy is useful because it is convenient to move large distances, where it is changed to heat energy (toaster), light energy (bulbs), or mechanical energy (electric motor). Thermal Energy to Electrical Energy From Science 7 – thermal energy = heat. A thermocouple is a device which converts heat to electrical energy. Thermocouples are made up of a loop of two wires made of two different metals. When they experience a temperature change, they generate a voltage, which in turn produces a weak electric current. This is called the Seebeck Effect. Thermo-Electric Generators A T.E. generator is a device which transforms heat energy into useful, useable electrical energy. An example of a TEG is a thermopile. A thermopile is a collection of thermocouples connected in series or in parallel to amplify the amount of electricity that is produced. The same principles work here. See fig 4.25 on p. 295. Piezoelectric Effect Movement or vibration (mechanical energy) caused by an electrical current. A special crystal that can expand or contract when experiencing a current. When touching some other object, the contact can cause sound waves to form, like in greeting cards. This technology is also used in electric watches. Electrical to Light Energy LEDs – Light emitting diodes – a semiconductor chip glows when a current is passed through it. This arrangement is much more efficient than traditional incandescent and even fluorescent lights. Light to Electrical Energy Photovoltaic Effect – By shining high intensity light on semiconductors, electrons are ‘shaken loose’ and flow freely through a metal wire where they will reach the load. The PV effect has been used to create PV or solar cells, and solar arrays which power everything from calculators to the International Space Station. Bioelectricity: The Electric Eel Not really an eel, but a knife-fish. Contains specialized muscle cells called electroplaques which, in total, can produce a voltage of 600 V. This voltage produces a large enough electric shock to stun or kill its prey.