i design an experiment in which i wanted to see which renewable energy sources can give out more voltage. sources that we used was a wind turbine, a hydrogen fuel cell, a solar panel and batteries(im not so sure if the batteries are the control variable). The voltage that we used to test each one was 20V DC (using a voltage meter). I'm getting kinda confused because i was looking for a definition of control variable and it said was sounding more like a definition for constant. so i don't know if the control are one of the energy sources or is it the voltage that we used. pls? help me
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definitely the batteries, they are a know value and you can measure the others as departures (+ or -) from the batteries.
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Batteries? Everyone uses batteries. So wouldn't the wind turbine and solar panel show other choices?