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Unit 5: Electromagnetism, a, Electromagnetism is, study of electromagnetic force, a, branch of physics involving the, type of physical, occurs between electrically charged, magnetism, two aspects, interaction that, are, particles. Electricity and, of electromagnetism., Magnetic field &, space, The, around, a, magnetic effect can be, the magnetic field., magnet in which its, experienced is called, The SI, Unit, of strength, %, magnetic induction, magnetic field, magnetic, (also known, or, as, induction field of magnetic flux density) is tesla (T)., It can, be measured in terms, of force on, charge moving inside the magnetic field or, concept of magnetic flux linked, the, by using, with a surface., 1 tesla (T) = 1 newton ampere ¹ metre" (NA" m²¹), Wb m-2), 1 weber metre -2 ( Wb m, =, It is represented by, B, lines, Magnetic, of force :, Magnetic field lines, are, limaginary lines used to, represent magnetic fields. They describe the direction of, The magnetic force, given position., on, a, north monopole at, any, Properties of magnetic field lines, ;, 17 They never, cross each other, 27, The density of field lines indicates the strength of, the field.

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3 Magnetic field lines always make closed - loops., 47 They originate / emerge from the north pole and, terminate at the south-pole outside the body of, the magnet;, 5> The tangent to the magnetic field lines at, any point gives the direction, field at that point., of magnetic, Magnetic intensity = (H), can, a, magnetic field, The degree to which, magnetise a substance (or) the capability of the, magnetic field to magnetise the substance is, represented in terms of magnetic intensity, Bo= magnetic field inside, a, vacuum, then, Bo, H =, where, M₂ = 47 x 107 tesla metre ampere is the, absolute permeability of vacuum., SI, unit of magnetic field (B) is tesla, .., Unit, H, &, testa, [H], - атрече, testa metre ampere, also known as, H-field (ar), * Magnetic intensity, magnetising field., Intensity of magnetisation (or) Magnetisation (I) =, It is defined as the magnetic moment, developed per unit volume, when, material is subjected to, field. It is denoted by I, magnetic, magnetising, a, metre" (Am)

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a, volume V, of, acquires, magnetising field, then, sample of magnetic material, magnetic dipole moment M due to the, of, I =, M, V, 2, SI unit, magnetic moment is ampere metre,, .. the, SI, unit, magnetisation, y is, off, [1], metre' (Am-1), metre, ampere, =, =, ampere, metre 31, have, and, (ie) magnetisation, magnetic intensity, same, units, called, is, simply, * The intensity of magnetisation, magnet's, ation., Magnetic flux ($), a, Magnetic flux through, is defined, lines passing, the, number, as, of magnetic field, normally through the surface. It is denoted by &., 55 is held in, a, mag-, a, area, surface, If, netic field is, then the magnetic flux passing, normally through the, 9 = B. AS, surface, is given by, The, SI, unit of magnetic flux is weber (wb)., Magnetic flux density @r) magnetic field (B) =, It is defined, as, unit, the magnetic flux per, normally through the magnetic substance., area, surface

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It is denoted by B., Magnetic flux density (or) magnetic field es, also, known, as magnetic induction., The magnetic induction B, is given by the, inside., a, substance, magnetised, the magnetic, sum of, field B. and magnetic field M. I produced due, to the magnetisation of the substance. Thus,, B = B₂+ M₂ I, = M₂H + M₂ I, B = M₂ (H+1), Mo, SI, unit, of magnetic field is tesla (T), weber metre -2 CWb m-²), (ar), Magnetic, Permeability : (M), It is, the ability of a material to allow the, lines, passage of magnetic, (ie) the degree, extent to, of force through it, which magnetic field, or, can penetrate or permeate, a material., the, ratio, It is defined as, induction to, of magnetic, the, magnetic intensity. It is denoted, by M. Thus,, B, M, H, a material, is defined, *, Relative permeability of, as the, magnetic permeability in medium, vacuum, to magnetic permeability in, (i.e), Мо, = M, 1, (or), M = My Mo, The, (or), M₂

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Magnetic susceptibility = (X₂), 음, a, The magnetic susceptibility of, is defined as, tisation to the magnetic intensity, magnetic, the magne-, substance, the, ratio, Thus,, I, Xm, -, H, * It is a, property, magnetic material, which determines how easily a, be magnetised., ican, Classification of magnetic material's, placed in, are, Faraday divided different substances into three, Categories according to the magnetic behaviour when, the magnetic field. They, 1) Diamagnetic substances, 1/ Paramagnetic substances, iliy Ferromagnetic substances., i) Dia magnetic :, Those substances, which when, field are, placed in a magnetic, direction opposite, called diamagnetic, a, weakly magnetised in, the magnetising field, to that, are, of, substances.", when placed inside an external magnetic field,, the magnetic field inside the diamagnetic is found, to be slightly less than the, external magnetic field., Examples of diamagnetic substances are, gold, glass, water, helium etc., соррея,, a, diamagnetic substance :, Properties of, 17 Diamagnetic substances, magnet., are, weakly repelled by, a