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copper
The bar magnet is what is termed a permanent magnet . This means that it is "always on" and can be used to do things like pick up paper clips. The electromagnet is created by winding a coil of wire about a ferromagnetic core and running a direct current through that coil. Only when the current is flowing will the electromagnet be operating. With the current switched off, the magnetic field around the coil of wire disappears, and the power of the electromagnetic disappears as well.There are some "fine points" associated with a further extension of this post, but the basic answer to the question is as written.A bar magnet is made from magnet materials and has a magnetic field at all times. An electromagnetic is not naturally magnet and only has a magnetic field when electricity is passed through it.
Uranus NOVEL STARS ANSWER: None of these
I'm not sure what "shape" means as applied to a magnetic field, which is not a physical object. To the extent I can conceive of them having a shape, the shape depends on the shape of the magnet, or more precisely upon the geometry of the poles of the magnet.
Movement of a wire in a magnetic field. If a loop of wire is moved in a magnetic field, it produces a voltage across its ends that can be measured on a voltmeter, resulting from the change in the magnetic flux linking the coil. If a resistor is connected across the ends, a current will flow and a force is needed to move the wire in the magnetic field. The energy supplied by the movement of the coil appears as electrical energy in the resistor, heating it up. That is the principle of an electric generator.
copper
the magnetic field
The bar magnet is what is termed a permanent magnet . This means that it is "always on" and can be used to do things like pick up paper clips. The electromagnet is created by winding a coil of wire about a ferromagnetic core and running a direct current through that coil. Only when the current is flowing will the electromagnet be operating. With the current switched off, the magnetic field around the coil of wire disappears, and the power of the electromagnetic disappears as well.There are some "fine points" associated with a further extension of this post, but the basic answer to the question is as written.A bar magnet is made from magnet materials and has a magnetic field at all times. An electromagnetic is not naturally magnet and only has a magnetic field when electricity is passed through it.
Uranus NOVEL STARS ANSWER: None of these
Electromagnet. it is a piece of metal (usually iron) that is wrapped in copper wire. it is turned on by putting electricity through the copper wire. it then producces a magnetic field when electricity is run through it.
I'm not sure what "shape" means as applied to a magnetic field, which is not a physical object. To the extent I can conceive of them having a shape, the shape depends on the shape of the magnet, or more precisely upon the geometry of the poles of the magnet.
Even a single atom (if it is the right kind of atom) can generate a magnetic field, so there can be any number of atoms in a magnet, from one onwards to very large numbers, such as 1025.
Plain old electricity. There's only one kind.
Movement of a wire in a magnetic field. If a loop of wire is moved in a magnetic field, it produces a voltage across its ends that can be measured on a voltmeter, resulting from the change in the magnetic flux linking the coil. If a resistor is connected across the ends, a current will flow and a force is needed to move the wire in the magnetic field. The energy supplied by the movement of the coil appears as electrical energy in the resistor, heating it up. That is the principle of an electric generator.
Magnetic field are unaffected by those materials. Magnets and electrical fields in general are only effected by other magnetic fields. Think of a compass that is brought near another magnet. Magnetic fields are exponential in strength meaning that they are most strong at the surface and quickly fade with distance. Dont have the equation but its simple and straight forward. So if you want a magnetic field to extend through a thick (5mmm) cardboard or plastic you will need larger more powerful magnets such as rare earth or neodymium magnets. Its really about the strength of the magnet and the distance of the magnetic field. Hope that helps.
Magnet* does*, and i gives off magnetic energy.
Changing the amount of magnetic field (known as "flux") through a conductor exerts a force on charged particles (electrons in the wire). A change in magnetic field strength in a region of space induces an electric field which circles the magnetic field lines, surprisingly whether or not there is a conductor there or not. It turns out that magnetism and electricity are inherently linked, they are kind of manifestations of the same thing. If "something" has the property of electric charge, it creates an electric field. If that something moves, it creates a magnetic field.