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#superconductor

3 public questions tagged with this topic.

Earth's Magnetism and Magnetic Declination

Which material has \( \chi = -1 \) and completely expels magnetic field lines?

**Elements of Earth's field** include declination D, inclination I, horizontal component B_H, total field B = √(B_H² + B_V²). B_H provides compass direction, declination varies with location, important for navigation, inclination 0° at magnetic equator, 90° at poles. Superconductors have chi = -1 and exhibit perfect diamagnetism, expelling all magnetic field lines (Meissner effect). Substituting values gives Superconductor, 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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Magnetic Field Lines, Bar Magnet and Dipole Moment

A material that completely expels magnetic field lines from its interior when cooled to a very low temperature is likely

**Magnetic field lines** form continuous closed loops, direction given by tangent at point, density indicates field strength. Unlike electric field lines, magnetic lines never intersect because unique field direction exists at each point, and bar magnet possesses dipole moment m = N I A directed from south to north pole inside magnet. Superconductors exhibit perfect diamagnetism (Meissner effect) when cooled below their critical temperature, expelling all magnetic field lines from their interior. This is due to induced surface currents that cancel the internal field, a property unique to super

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 superconductor has a susceptibility \( \chi \) of:

**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). Superconductors exhibit perfect diamagnetism with chi = -1 , as the magnetic field is completely expelled (Meissner effect). Substituting values gives -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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