Category: magnetically levitated trains

What is the dangerous part of electricity: charge, current, voltage, or what?

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What is the dangerous part of electricity: charge, current, voltage, or what?

Current is ultimately the killer. A current of about 30 milliamperes is potentially lethal when applied across your chest. But your body is relatively insulating, so sending that much current through your chest isn’t easy. That’s where voltage comes in. The higher the voltage on a wire, the more energy each charge on the wire has and the more likely that it will be able to pierce through your skin and travel through your body. Thus it’s a combination of voltage and current that is dangerous. Current kills, but it needs voltage to propel it through your skin.

What is the difference between current and voltage?

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What is the difference between current and voltage?

Current measures the amount of (positive) charge passing a point each second. If many charges pass by in a short time, the current is large. If few charges pass by in a long time, the current is small. Voltage measures the energy per charge. If a small number of (positive) charges carry lots of energy with them (either in their motion as kinetic energy or as electrostatic potential energy), their voltage is high. If a large number of charges carry little energy with them, their voltage is low.

What is the difference between fields and charges (magnetic and electric)?

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What is the difference between fields and charges (magnetic and electric)?

Electric charges themselves push and pull on one another via electrostatic forces. Magnetic poles push and pull on one another via magnetostatic forces. We can also think of the forces that various electric charges exert on one charge that you’re hold as being caused by some property of the space at which that one charge is located. We call that property of space an electric field and say that the charge is being pushed on by the electric field. We could do the same with magnetic poles and a magnetic field. But these two fields are more than just a useful fiction. The fields themselves really do exist. You can see that whenever moving electric charge creates a magnetic field or when a moving magnetic pole creates an electric field. Light consists only of electric and magnetic fields.

What materials are magnets made of?

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What materials are magnets made of?

They are mostly iron, cobalt, or nickel, which are intrinsically magnetic metals. But to help them retain their magnetic alignments, permanent magnets have other elements in them, too. Iron is magnetic at the microscopic scale, but that magnetism is broken up into lots of tiny regions that all point in random directions. To make a whole piece of iron magnetic, something must help those tiny regions stay pointing in the same direction. The good permanent magnets have structures that keep all the tiny regions pointing in one direction.