I'm thinking about building a generator for my parents powered by a stream in their backyard. It would be a great way to learn about science. I'm trying to find the relevant equations so that I can estimate how much energy the stream produces. Right now I have this equation: ε = NBAω I don't understand the difference between voltage and EMF, they seem like the same thing to me. The stream is about 3 feet wide by 6 inches deep and I don't know how much volume flows through it per second, but using this wiki article http://en.wikipedia.org/wiki/Streamflow it looks like I can find out. The it seems that I would need another equation to figure out how many revolutions per minutes I could get in the turbine. I would imagine that the energy or work generated by water would be equal to mass times gravity times distance times a friction coefficient. So then I would need some equation to figure out how energy efficient the turbine is unless that's covered by the friction coefficient. I have no idea about that. I'm not sure how to figure out fast I could get the turbine flowing. I also don't know what a reasonable amount of B (magnetic field I could produce). Wouldn't I have to buy the magnets and figure out what Tesla's they are? As far as the A (area) part of the equation, I would think that something 3 feet by 2 feet would be reasonable, right? As for the N (number of turns) part of the equation, I don't really know how to estimate that.