1. ### B Small powerful electro magnet

Hello, i need a small electro magnet with it's dimension not bigger than 8 millimetre (0,31 inch) in diameter with a length under 10 millimetre (0,39 inch). I want it to be as powerful as possible, where do i find such magnets? And how should i make my own? How powerful is it possible to make...
2. ### Factors affecting wind turbine cut in speed

Hello, could someone explain some of the factors, or the calculation, for determining wind turbine cut in speed? I am talking about small wind turbines using with a single bearing on the rotating axis and a permanent magnet generator. A lot of literature targets a cut in speed of 3 m/s without...
3. ### Looking for flexible seal for oscillating thin opening

Hello Everyone, I'm looking for a sealing membrane, or comparable solution, to seal a thin opening (~15mm x 2mm) that oscillates elliptically, like in my example picture below, with a low amplitude (+/- 1mm) and frequency in the 100s - 1000s of Hz range. Any ideas?
4. ### Nano Fusion? Micro Fusion? Fusion Learning Source?

When experimenting with fusion, why do we always go so big and make extremely expensive reactors that take years to create and even construct facilities for? I've seen some failed attempts at making fusion happen in carbon nanotubes, failing in the sense that the carbon nanotubes are just...
5. ### Small Angle Approximation in Single Slit Interference

Homework Statement A monochromatic light source is used with a double slit to create an interference pattern on a screen that is 2.00 meters away. If the 2nd bright spot is observed 8.73 mm above the central maximum, can the small angle approximation be used? Show and/or explain your reasoning...
6. ### Solar updraft tower: How small a working unit can be made?

solar updraft tower: How small a working unit can be made? My reason to ask this question is: I think that if a commercial unit is ever to be built, first the concept must be widely established. One or two working examples of a size similar to the prototype built in Spain won't likely prove...