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View Full Version : Would a charged gyroscope act as a magnet?

WaxRubiks
2008-Oct-02, 06:42 AM
I just wondered whether, if you had a gyroscope with a plastic rim that you could charge with static electricity, and then you set it spinning, held above the ground by a piece of string, so that its axis was aligned with the tangent to the Earth; whether that would act like a magnetic compass?

hhEb09'1
2008-Oct-02, 06:53 AM
The effect of the gyroscope would probably predominate, surely. I'd suppose it would depend upon the construction details. Here (http://en.wikipedia.org/wiki/Gyrocompass) is a wiki article about gyrocompasses.

astromark
2008-Oct-02, 06:53 AM
Umm... No.

Attempting to align a gyroscope could be hazardous. As a child I had the wheel of a push bike hanging from the rafters in a shed... when I spun it there was a Earthquake...I have not ever played with gyros again...:)

The fact is that a spinning gyroscope has its own idea of stability. Magnetic force does little to altar that.

cjameshuff
2008-Oct-02, 01:29 PM
I just wondered whether, if you had a gyroscope with a plastic rim that you could charge with static electricity, and then you set it spinning, held above the ground by a piece of string, so that its axis was aligned with the tangent to the Earth; whether that would act like a magnetic compass?

A charged gyroscope will produce a magnetic field, but a weak one. It might affect a compass, but the gyro forces would prevent it from acting like one. Without gravity, or other interfering forces, it would slowly precess to point magnetic north and south, but in reality, something else is likely to interfere.

Think about the amount of charge in motion relative to the amount of mass. Protons and neutrons are 1836 times as massive as electrons, and even in a highly charged object, most atoms are neutral.

papageno
2008-Oct-02, 04:34 PM
I just wondered whether, if you had a gyroscope with a plastic rim that you could charge with static electricity, and then you set it spinning, held above the ground by a piece of string, so that its axis was aligned with the tangent to the Earth; whether that would act like a magnetic compass?

The charge on the rim would move in circle, and therefore it would be equivalent to a loop of metallic wire in which a current flows.
Therefore your charged gyroscope would have a magnetic moment.

This magnetic moment would be affected by the Earth's magnetic field. The resulting force would then compete with the rotational inertia of the gyroscope.

The resulting motion depends on the moment of inertia of the gyroscope, its rotational speed, and the amount of charge. Probably somebody has made some homework exercise for students.

mugaliens
2008-Oct-02, 05:50 PM
I just wondered whether, if you had a gyroscope with a plastic rim that you could charge with static electricity, and then you set it spinning, held above the ground by a piece of string, so that its axis was aligned with the tangent to the Earth; whether that would act like a magnetic compass?

The charged edge, rotating through space, would act identically to a current travelling in a circle, exactly like a loop of wire through which a current is travelling.

And it would produce the same magnetic field as would such as loop of wire.

It would not do you much good as a gyrocompass, however, as the internia from the gyroscopic effect would far exceed any magnetic orientation effect.