#paramagnetism

Earth's Magnetism and Magnetic Declination

A paramagnetic material with \( \chi = 3 \times 10^{-3} \) in \( H = 400 \, \text{A m}^{-1} \) has magnetization \( M \)

**Geomagnetic field** arises from outer core dynamo, field lines emerge near geographic south pole. Understanding D and I allows conversion between geographic and magnetic coordinates, with B_H = B cos(inclination) used in experiments with tangent galvanometer. M = chi H . Given: chi = 3 × 10⁻³ , H = 400 A m⁻¹ . M = 3 × 10⁻³ × 400 = 1.2 A m⁻¹ . Substituting values gives 1.2 A m⁻¹, which matches expected magnitude for this magnetic configuration, confirming dipole field dependence on m/r³ and torque relation τ = m B sinθ.

Ref: NCERT > Physics Book > Magnetism and Matter > Earth's Magnetism and Magnetic Declination

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Earth's Magnetism and Magnetic Declination

A paramagnetic material with \( \chi = 4 \times 10^{-4} \) in \( H = 2000 \, \text{A m}^{-1} \) has magnetization \( M \

**Geomagnetic field** arises from outer core dynamo, field lines emerge near geographic south pole. Understanding D and I allows conversion between geographic and magnetic coordinates, with B_H = B cos(inclination) used in experiments with tangent galvanometer. M = chi H . Given: chi = 4 × 10⁻⁴ , H = 2000 A m⁻¹ . M = 4 × 10⁻⁴ × 2000 = 0.8 A m⁻¹ . Substituting values gives 0.8 A m⁻¹, which matches expected magnitude for this magnetic configuration, confirming dipole field dependence on m/r³ and torque relation τ = m B sinθ.

Ref: NCERT > Physics Book > Magnetism and Matter > Earth's Magnetism and Magnetic Declination

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Hysteresis, Retentivity, Coercivity and Permanent Magnets

A paramagnetic material with \( \chi = 8 \times 10^{-4} \) in \( H = 2500 \, \text{A m}^{-1} \) has magnetization \( M \

**Hysteresis loop** plots B versus H for ferromagnetic material, retentivity (remanence) is residual B at H=0 after saturation, coercivity is reverse H needed to reduce B to zero. Hard ferromagnets have high retentivity and coercivity, retaining strong magnetism after external field removed, suitable for permanent magnets. M = chi H . Given: chi = 8 × 10⁻⁴ , H = 2500 A m⁻¹ . M = 8 × 10⁻⁴ × 2500 = 2 A m⁻¹ . Substituting values gives 2.0 A m⁻¹, which matches expected magnitude for this magnetic configuration, confirming dipole field dependence on m/r³ and torque relation τ = m B sinθ.

Ref: NCERT > Physics Book > Magnetism and Matter > Hysteresis, Retentivity, Coercivity and Permanent Magnets

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Hysteresis, Retentivity, Coercivity and Permanent Magnets

The reason a paramagnetic material’s magnetization increases with a stronger external field is:

**Soft ferromagnetic materials** have low coercivity and retentivity, narrow hysteresis loop, lose magnetism when external field removed, ideal for electromagnets and transformer cores. Energy loss per cycle proportional to loop area, explaining why soft materials minimize loss. In paramagnetic materials, magnetization increases with a stronger external field because more atomic magnetic moments align with the field, overcoming random thermal motion, though the alignment remains partial compared to ferromagnetic materials. Substituting values gives Increased moment alignment, which matches exp

Ref: NCERT > Physics Book > Magnetism and Matter > Hysteresis, Retentivity, Coercivity and Permanent Magnets

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Diamagnetism, Paramagnetism and Ferromagnetism

A paramagnetic material has \( \chi = 5 \times 10^{-4} \) and \( H = 2 \times 10^3 \, \text{A m}^{-1} \). What is its ma

**Diamagnetism** exhibits small negative susceptibility χ ≈ -10⁻⁵ to -10⁻⁶, weakly repelled from stronger to weaker field regions, no permanent moment, induced moment opposite to B, present in all materials but dominated by other effects. Superconductor perfect diamagnet with χ = -1, complete field expulsion. M = chi H . Given: chi = 5 × 10⁻⁴ , H = 2 × 10³ A m⁻¹ . Substitute: M = 5 × 10⁻⁴ × 2 × 10³ = 1 A m⁻¹ . Substituting values gives 1 A m⁻¹, which matches expected magnitude for this magnetic configuration, confirming dipole field dependence on m/r³ and torque relation τ = m B sinθ.

Ref: NCERT > Physics Book > Magnetism and Matter > Diamagnetism, Paramagnetism and Ferromagnetism

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Diamagnetism, Paramagnetism and Ferromagnetism

A material’s weak enhancement of the magnetic field inside it is due to:

**Ferromagnetism** shows large positive χ ≈ 10³ to 10⁵, strong attraction, domain structure with spontaneous magnetization, hysteresis, retentivity. Distinction based on sign and magnitude of χ and behaviour in non-uniform field, explaining attraction versus repulsion. Paramagnetic materials weakly enhance the magnetic field inside them because their atomic magnetic moments partially align with the external field, producing a small positive magnetization that adds to the applied field. Substituting values gives Weak alignment of atomic moments, which matches expected magnitude for this magneti

Ref: NCERT > Physics Book > Magnetism and Matter > Diamagnetism, Paramagnetism and Ferromagnetism

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Diamagnetism, Paramagnetism and Ferromagnetism

A paramagnetic material with \( \chi = 9 \times 10^{-4} \) in \( H = 2000 \, \text{A m}^{-1} \) has magnetization \( M \

**Ferromagnetism** shows large positive χ ≈ 10³ to 10⁵, strong attraction, domain structure with spontaneous magnetization, hysteresis, retentivity. Distinction based on sign and magnitude of χ and behaviour in non-uniform field, explaining attraction versus repulsion. M = chi H . Given: chi = 9 × 10⁻⁴ , H = 2000 A m⁻¹ . M = 9 × 10⁻⁴ × 2000 = 1.8 A m⁻¹ . Substituting values gives 1.8 A m⁻¹, which matches expected magnitude for this magnetic configuration, confirming dipole field dependence on m/r³ and torque relation τ = m B sinθ.

Ref: NCERT > Physics Book > Magnetism and Matter > Diamagnetism, Paramagnetism and Ferromagnetism

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Diamagnetism, Paramagnetism and Ferromagnetism

Which material has \( \chi \) slightly positive and moves from weaker to stronger field regions?

**Paramagnetism** has small positive χ ≈ 10⁻³ to 10⁻⁵, weakly attracted towards stronger field, random moments align partially with B, magnetization decreases with temperature following Curie law χ ∝ 1/T. Materials have unpaired electrons with permanent moments. Paramagnetic materials have a small positive chi and are weakly attracted from weaker to stronger magnetic field regions. Substituting values gives Paramagnetic, which matches expected magnitude for this magnetic configuration, confirming dipole field dependence on m/r³ and torque relation τ = m B sinθ.

Ref: NCERT > Physics Book > Magnetism and Matter > Diamagnetism, Paramagnetism and Ferromagnetism

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Magnetization, Magnetic Intensity, Susceptibility and Permeability

Which material has a small positive \( \chi \) and aligns weakly with an external magnetic field?

**Relation between B, H, M** is B = μ₀(H+M) = μ₀(1+χ)H. Susceptibility χ = μ_r -1 quantifies material response. Given B, μ_r, n, current I = B/(μ₀ μ_r n), with μ₀ = 4π×10⁻⁷ T·m/A, enabling current calculation for desired B with magnetic core. Paramagnetic materials have a small positive chi and align weakly with an external magnetic field due to the alignment of atomic dipoles. Substituting values gives Paramagnetic, which matches expected magnitude for this magnetic configuration, confirming dipole field dependence on m/r³ and torque relation τ = m B sinθ.

Ref: NCERT > Physics Book > Magnetism and Matter > Magnetization, Magnetic Intensity, Susceptibility and Permeability

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Magnetic Field Lines, Bar Magnet and Dipole Moment

A material placed in a magnetic field increases the field inside it slightly and moves toward stronger field regions. Th

**Magnetic dipole moment** quantifies strength and orientation of magnet, m = 2l × q_m where q_m pole strength. Field line concept visualizes B, with closed nature reflecting absence of magnetic monopoles, explaining non-intersection and continuity. Paramagnetic materials have a small positive susceptibility ( chi > 0 ), causing a slight enhancement of the magnetic field inside them due to the weak alignment of atomic magnetic moments with the external field. They are attracted to regions of stronger field strength. Substituting values gives Paramagnetic materials, which matches expected magni

Ref: NCERT > Physics Book > Magnetism and Matter > Magnetic Field Lines, Bar Magnet and Dipole Moment

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Magnetization, Magnetic Intensity, Susceptibility and Permeability

A paramagnetic material with \( \chi = 7 \times 10^{-4} \) in \( H = 3000 \, \text{A m}^{-1} \) has magnetization \( M \

**Magnetization M** is magnetic moment per unit volume (A/m), magnetic intensity H = B/μ₀ - M, susceptibility χ = M/H dimensionless, permeability μ = B/H = μ₀(1+χ), relative permeability μ_r = μ/μ₀ = 1+χ. For solenoid with core, B = μ₀ μ_r n I, n turns per meter (m⁻¹), I current (A). M = chi H . Given: chi = 7 × 10⁻⁴ , H = 3000 A m⁻¹ . M = 7 × 10⁻⁴ × 3000 = 2.1 A m⁻¹ . Substituting values gives 2.1 A m⁻¹, which matches expected magnitude for this magnetic configuration, confirming dipole field dependence on m/r³ and torque relation τ = m B sinθ.

Ref: NCERT > Physics Book > Magnetism and Matter > Magnetization, Magnetic Intensity, Susceptibility and Permeability

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Magnetic Field Lines, Bar Magnet and Dipole Moment

A material’s weak attraction to a magnetic field is due to:

**Magnetic dipole moment** quantifies strength and orientation of magnet, m = 2l × q_m where q_m pole strength. Field line concept visualizes B, with closed nature reflecting absence of magnetic monopoles, explaining non-intersection and continuity. Paramagnetic materials exhibit weak attraction to a magnetic field because their atomic or molecular magnetic moments, which are randomly oriented in the absence of a field, partially align with an external field, producing a small positive magnetization. Substituting values gives Partial alignment of atomic magnetic moments, which matches expected

Ref: NCERT > Physics Book > Magnetism and Matter > Magnetic Field Lines, Bar Magnet and Dipole Moment

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