Sagot :
Answer:
Magnetic fields occur whenever charge is in motion. As more charge is put in more motion, the strength of a magnetic field increases. Magnetism and magnetic fields are one aspect of the electromagnetic force, one of the four fundamental forces of nature.
Explanation:pa brainliest po
G, b, i, t, slash, i, n, c, h, squared between 1991 and 2003 [2]). In 2007 Albert Fert and Peter Grünberg were awarded the Nobel Prize in Physics for this discovery.
In the SI system, the magnetic field is measured in tesla (symbol \mathrm{T}TT, named after Nikola Tesla). The Tesla is defined in terms of how much force is applied to a moving charge due to the field. A small refrigerator magnet produces a field of around 0.001~\mathrm{T}0.001 T0, point, 001, space, T and the Earth's field is about 5\cdot 10^{-5}~\mathrm{T}5⋅10
−5
T5, dot, 10, start superscript, minus, 5, end superscript, space, T. An alternative measurement is also often used, the Gauss (symbol \mathrm{G}GG). There is a simple conversion factor, 1~\mathrm{T} = 10^4~\mathrm{G}1 T=10
4
G1, space, T, equals, 10, start superscript, 4, end superscript, space, G. Gauss is often used because 1 Tesla is a very large field.
In equations the magnitude of the magnetic field is given the symbol BBB. You may also see a quantity called the magnetic field strength which is given the symbol HHH. Both BBB and HHH have the same units, but HHH takes into account the effect of magnetic fields being concentrated by magnetic materials. For simple problems taking place in air you won't need to worry about this distinction.
What is the origin of the magnetic field?
Magnetic fields occur whenever charge is in motion. As more charge is put in more motion, the strength of a magnetic field increases.
Magnetism and magnetic fields are one aspect of the electromagnetic force, one of the four fundamental forces of nature.
There are two basic ways which we can arrange for charge to be in motion and generate a useful magnetic field:
We make a current flow through a wire, for example by connecting it to a battery. As we increase the current (amount of charge in motion) the field increases proportionally. As we move further away from the wire, the field we see drops off proportionally with the distance. This is described by Ampere's law. Simplified to tell us the magnetic field at a distance rrr from a long straight wire carrying current III the equation is
B = \frac{\mu_0 I}{2 \pi r}B=
2πr
μ
0
I
B, equals, start fraction, mu, start subscript, 0, end subscript, I, divided by, 2, pi, r, end fraction
Here \mu_0μ
0
mu, start subscript, 0, end subscript is a special constant known as the permeability of free space. \mu_0 = 4\pi\cdot 10^{-7}~\mathrm{T\cdot m / A}μ
0
=4π⋅10
−7
T⋅m/Amu, start subscript, 0, end subscript, equals, 4, pi, dot, 10, start superscript, minus, 7, end superscript, space, T, dot, m, slash, A. Some materials have the ability to concentrate magnetic fields, this is described by those materials having higher permeability.
Since the magnetic field is a vector, we also need to know the direction. For conventional current flowing through a straight wire this can be found by the right-hand-grip-rule. To use this rule imagine gripping your right hand around the wire with your thumb pointing in the direction of the current. The fingers show the direction of the magnetic field which wraps around the wire. [Explain]
Right-hand-grip rule used to find the direction of the magnetic field (B) based on the direction of a current (I). [3]
Right-hand-grip rule used to find the direction of the magnetic field (B) based on the direction of a current (I). [3]
Figure 4: Right-hand-grip rule used to find the direction of the magnetic field (B) based on the direction of a current (I). [3]
We can exploit the fact that electrons (which are charged) appear [explain appear] to have some motion around the nuclei of atoms. This is how permanent magnets work. As we know from experience, only some 'special' materials can be made into magnets and some magnets are much stronger than others. So some specific conditions must be required:
Although atoms often have many electrons, they mostly 'pair up' in such a way that the overall magnetic field of a pair cancels out. Two electrons paired in this way are said to have opposite spin. So if we want something to be magnetic we need atoms that have one or more unpaired electrons with the same spin. Iron for example is a 'special' material that has four such electrons and therefore is good for making magnets out of. [Explain 'pairing up']
Even a tiny piece of material contains billions of atoms. If they are all randomly orientated the overall field will cancel out, regardless of how many unpaired electrons the material has. The material has to be stable enough at room temperature to allow an overall preferred orientation to be established. If established permanently then we have a permanent magnet, also known as a ferromagnet.
Explanation: