Right my question is can you produce a self perpetuating electric dynamo in space?
Okay so as far as I know an object in space will continue to move in one direction at the same speed because there is little to no inertia in space other than the pull of gravity from bodies of planets and stars ect. If I remember GCSE physics with electric dynamos a magnet spins within a tube of wiring producing electricity.
Couldn't there be a perpetually spinning dynamo in space. Spinning at the same rate continuesly producing electricity?
Okay so as far as I know an object in space will continue to move in one direction at the same speed because there is little to no inertia in space other than the pull of gravity from bodies of planets and stars ect. If I remember GCSE physics with electric dynamos a magnet spins within a tube of wiring producing electricity.
Couldn't there be a perpetually spinning dynamo in space. Spinning at the same rate continuesly producing electricity?
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There are two problems with your proposed device.
The first, as has already been pointed out, is friction (which is virtually always present in any practical system) - this will cause your dynamo to gradually slow down and warm up.
However, even if you could eliminate friction entirely (say, with magical bearings) the laws of physics are still not going to allow you to get energy from nothing. If you have a load connected to the terminals of your dynamo, then current will flow. The magnet in the dynamo will exert a torque on the current flowing through the armature coil. This torque, it just so happens, acts against the rotation and slows the dynamo down (this is a special case of Lenz's law). Eventually, the system comes to a halt.
In the ideal, frictionless case what your basically doing is this: you manually exert a torque on the armature to get it spinning, putting kinetic energy into the dynamo. You draw out electrical energy by connecting a load across the terminals. Once the electrical energy output is equal to the initial kinetic energy input, the dynamo will have slowed to a halt.
So, sadly, the maxim "there is no such thing as a free lunch" holds true.
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ETA: Hah, I just realised I have described a spinning loop of wire with a stationary magnet (usually you'd have a spinning magnet and a stationary loop of wire). Nevertheless, the physics is just the same: Lenz's law conspires to slow the dynamo down once you connect a load and current starts to flow.
The first, as has already been pointed out, is friction (which is virtually always present in any practical system) - this will cause your dynamo to gradually slow down and warm up.
However, even if you could eliminate friction entirely (say, with magical bearings) the laws of physics are still not going to allow you to get energy from nothing. If you have a load connected to the terminals of your dynamo, then current will flow. The magnet in the dynamo will exert a torque on the current flowing through the armature coil. This torque, it just so happens, acts against the rotation and slows the dynamo down (this is a special case of Lenz's law). Eventually, the system comes to a halt.
In the ideal, frictionless case what your basically doing is this: you manually exert a torque on the armature to get it spinning, putting kinetic energy into the dynamo. You draw out electrical energy by connecting a load across the terminals. Once the electrical energy output is equal to the initial kinetic energy input, the dynamo will have slowed to a halt.
So, sadly, the maxim "there is no such thing as a free lunch" holds true.
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ETA: Hah, I just realised I have described a spinning loop of wire with a stationary magnet (usually you'd have a spinning magnet and a stationary loop of wire). Nevertheless, the physics is just the same: Lenz's law conspires to slow the dynamo down once you connect a load and current starts to flow.
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When the spinning magnet induces a current in the field coils around it the magnetic field of that induced current opposes the rotation of the magnet so that you have to continuously do work on the magnet to keep it moving. (Conservation of Energy) As soon as you stop doing work on it the magnet stops rotating. There's no free lunch. :(
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You're trying to make a perpetuum mobile. It won't work, and it'll only end in tears.
Oh, and you're forgetting that even though there's no gravity (or only microgravity), there's still friction.
Oh, and you're forgetting that even though there's no gravity (or only microgravity), there's still friction.