Define the following term Electromagnets and magnetic keepers
with proper writing
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Answer:
Magnetic keeper.
A magnet keeper, also known historically as an armature, is a bar made from magnetically soft iron or steel, which is placed across the poles of a permanent magnet to help preserve the strength of the magnet by completing the magnetic circuit; it is important for magnets that have low magnetic coercivity, such as alnico magnets (0.07T).[1]
A "horseshoe magnet" made of Alnico 5, about 1 in high. The metal bar (bottom) is a keeper.
Keepers also have a useful safety function, as they stop external metal being attracted to the magnet.
Many magnets do not need a keeper, such as supermagnets, as they have very high coercivities; only those with lower coercivities, meaning that they are more susceptible to stray fields, require keepers.
A magnet can be considered as the sum of many little magnetic domains, which may be only a few microns or smaller in size. Each domain carries its own small magnetic field, which can point in any direction. When all the domains are pointing in the same direction, the fields add up, yielding a strong magnet. When these all point in random directions, they cancel each other, and the net magnetic field is zero.
In magnets with lower coercivities, the direction in which the magnetic domains are pointing is easily swayed by external fields, such as the Earth's magnetic field or perhaps by the stray fields caused by flowing currents in a nearby electrical circuit. Given enough time, such magnets may find their domains randomly oriented, and hence their net magnetization greatly weakened. A keeper for low-coercivity magnets is just a strong permanent magnet that keeps all the domains pointing the same way and realigns those that may have gone astray.
Electromagnets.
An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire wound into a coil. A current through the wire creates a magnetic field which is concentrated in the hole, denoting the centre of the coil. The magnetic field disappears when the current is turned off. The wire turns are often wound around a magnetic core made from a ferromagnetic or ferrimagnetic material such as iron; the magnetic core concentrates the magnetic flux and makes a more powerful magnet.
A simple electromagnet consisting of a coil of wire wrapped around an iron core. A core of ferromagnetic material like iron serves to increase the magnetic field created.[1] The strength of magnetic field generated is proportional to the amount of current through the winding.[1]
Magnetic field produced by a solenoid (coil of wire). This drawing shows a cross section through the center of the coil. The crosses are wires in which current is moving into the page; the dots are wires in which current is moving up out of the page.
The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be quickly changed by controlling the amount of electric current in the winding. However, unlike a permanent magnet that needs no power, an electromagnet requires a continuous supply of current to maintain the magnetic field.
Electromagnets are widely used as components of other electrical devices, such as motors, generators, electromechanical solenoids, relays, loudspeakers, hard disks, MRI machines, scientific instruments, and magnetic separation equipment. Electromagnets are also employed in industry for picking up and moving heavy iron objects such as scrap iron and steel.[2]
Explanation:
#Hope you have satisfied with this answer.
An electromagnet is a type of magnet in which
the magnetic field is produced by an electric current. Electromagnets usually consist of wire wound into a coil. A current through the wire creates a magnetic field which is concentrated in the hole, denoting the centre of the coil. The magnetic field disappears when the current is turned off. The wire turns are often wound around a magnetic core made from a ferromagnetic or ferrimagnetic material such as iron; the magnetic core concentrates the magnetic flux and makes a more powerful magnet.