Permeability
It has been found that if a soft iron rod called core is placed inside a solenoid, then the strength of the magnetic field becomes very large because the iron core is magnetized by induction The core of the electromagnet must be of soft iron because soft iron loses all of its magnetism when current in the coil is switched off or stopped
Provide amoving magnetic force field.
To increase the strength of a magnet you need to stack it between two stronger magnets or electromagnets. To weaken it, you'd have to heat it up, or use the same method as when strengthening, only this time you should flip the magnet so it would repel the stronger (electro)magnets.
As the distance from a charged particle increases the strength of its electric field DECREASES.
The magnitude of the electric potential is dependent upon the particle's charge and the electric field strength.
yes
A magnet can be theoretically used in any medium, but strength of the magnet will strongly be influenced by the magnetic permeability of that given medium.
The magnetic poles of the magnetic domains are physically jarred and realign. They realign randomly. When a material appears to be strongly magnetized it is because these domains are aligned.
yes*edit: don't confuse moving with changing. A change in magnetic field strength/direction will induce an electric current.
More electricity to, and/or more windings on, the coil.
Through a current in a conductor; it is strengthened once by making a coil of the conductor and then by inserting an easily magnetized core inside the coil
The strength of electromagnet depends on the electric current flowing through the core because when the current is stopped, the core is no longer magnetized and the rate of change of flux linkage.
yes*edit: don't confuse moving with changing. A change in magnetic field strength/direction will induce an electric current.
Permeability of the medium, that too, if it is ferro-magnetic material then it gets increased to a larger extent and so the magnetic induction too increases enormously.
Magnetic induction B = mu * n * I Here mu is the magnetic permeability of the core material. n - the number of turns per unit length and I - the current in ampere. So as number of turns increases the magnetic effect too increases
The mineral lodestone, also known as magnetite, is ferromagnetic, which means that it can be magnetized. Most of the magnetite found on Earth was magnetized by the Earth's magnetic field as the magnetite formed. Most naturally occurring lodestones are magnetized, but the strength of that magnetization is much less than any common magnet and can only be detected with sophisticated equipment. The invisible force is... magnetism.
I cannot remember for sure, but in an electromagnet, an aluminum core would not have any permeability to add to the electromagnet's strength. An electromagnet is more efficient when a thicker core is used; it generates more power. The material you use should be prone to magnetism, as in attracted by permanent magnetic apparatuses or the such. So, an aluminum bar/core (cannot be magnetized), like you stated, wouldn't be the best choice for your magnet's core.