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question regarding neodynium magnets


mrsmiley

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if you were to put one next to an electric meter,in theory what would happen?

 

It would jump to the motor case, if close enough. If close enough or attached to the housing or large enough, I imagine the motor might run rough, stop, or fail to start.

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By electric meter, I'm guessing an analog type ammeter. Which works by passing the electricity through an electromagnet, that then moves the needle to the appropriate current reading.

 

Applying an external magnetic field (via your magnet) would probably just move the needle, but there wouldn't be any current flowing through the meter.

 

You might break the device though, if it is delicate enough.

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......works by passing the electricity through an electromagnet, that then moves the needle to the appropriate current reading...

 

Applying an external magnetic field (via your magnet) would probably just move the needle, but there wouldn't be any current flowing through the meter.

 

 

If it is a coil inside then as you bring the magnet to the box, the lines of flux from the magnetic field of the magnet would cut the coil and cause some current to flow. When the magnet is stationary, then the current would stop.

 

Therefore, I reckon you would get a reading as the magnet approches. Nothing when the magnet stops. Then another reading as you draw the magnet away again, which would drop off rather quickly. (?)

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See, the problem is that in the analog meters, the current is used to generate a magnetic field. This magnetic field then pulls on the needle, which is attached to a spring. The more current, the stronger the field, the more it pulls the magnet and stretches the spring.

 

Since the device operates based on a magnetic field, applying an external field just hijacks the mechanism in the meter. Instead of the electromagnet pulling the needle, its the outside magnet. And a neodymium magnet would be more than strong enough to pull the needle off of the scale.

 

Technically, a small bit of current would be produced, but that effect will be swamped by the massive field of the external magnet.

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