|MadSci Network: Engineering|
Hi Cheng Ka Wing, I'll try to answer your questions below: > 1i)How electrical energy be stored? The usual way to store electrical energy is to convert it into a chemical energy form first (e.g. in a battery or as H2 after electro- lysis of water). This way it is stable and can be kept for long time. Electrical energy can directly be stored in capacitors for a short while (not more than a few seconds due to internal losses). > ii)in a chip Chips are designed to store or process electrical signals and not energy. In fact it is aim of chip development to decrease the amount of energy necessary to store or process signals as much as possible. I don't think chips could ever store considerable amounts of energy. > 2ai)Can sound energy be converted into electrical energy? Certain kinds of microphones convert sound into energy, but at very low efficiency, since again it is the signal that interests us, not the energy. Other kinds of microphones, which modulate a current and do not produce energy, work just as well for this purpose. I have not heard of any system developed to convert sound into elec- trical energy efficiently and I do not think it is worthwhile to de- velop one, since the amounts of energy available in the form of sound are rather small, even if it appears very loud to your ears (see below). > ii)if yes....how? By moving an electric conductor (e.g. a wire) through a magnetic field, some of the kinetic energy is converted to electricity and a voltage is induced in the conductor. Some kinds of microphones use this effect by having a wire coil excited by sound (waves of moving air particles) in the field of a build-in magnet. The resulting voltages are very small and need to be amplified to be usable. > bi)how to store the converted electrical energy? It is not worthwhile to store such tiny amounts of energy. Normally one is only interested in storing the information contained in the signal (e.g. voice recording), but that costs a lot more energy than the captured sound originally had. If you are 20m from the 40kW-speakers of a heavy metal concert, you easily become deaf. Yet if you have a 1m x 1m device that converts all incoming sound energy at 100% efficiency, you would get 10W of electrical power - a tenth of what an ordinary light bulb needs. Microphones have less than 1% efficiency and are much smaller ... > ii)in a chip ? Chips are not a medium of choice to store energy. See above. > 3)Is their anything that is very /extremely sensitive to sound? Microphones, human (and other) ears. Please let me know if you need further clarifications. Greetings from Singapore, Frank Berauer
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