A student makes an electromagnet by wrapping 320 turns of wire around a wooden cylinder diameter 4.20 cm. The coil is connected to a

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Ok, I hope, I think it correctly. If I am correct, z = distance from the electro-magnet on its axis and d = diameter. I hope that's okay. It would be useful to have an image.

so narrow, so it'd seem like they're not very efficient for catching the wind, whereas with an axial-flow electric fan (your traditional basic fan), the blades are rather wide, which seems to be because that'd make them more efficient because of more

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Different design constraints:

In either case, the blade is an airfoil (a wing). One may characterize an airfoil in terms of the ratio of its lift to its drag. A wing with a high ratio of lift to drag makes more of what you want and less