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#magnetic properties

10 public questions tagged with this topic.

Earth's Magnetism and Magnetic Declination

Which material retains magnetization after the external field is removed and is used in permanent magnets?

**Earth's magnetism** approximated as dipole inclined to rotation axis, magnetic declination is angle between geographic north and magnetic north, inclination or dip angle is angle between total field and horizontal. Horizontal component B_H = B cosδ, vertical B_V = B sinδ, δ dip angle, B_H ≈ 3-4×10⁻⁵ T in India. Ferromagnetic materials, particularly hard ferromagnets, retain magnetization after the external field is removed and are used in permanent magnets. Substituting values gives Ferromagnetic, which matches expected magnitude for this magnetic configuration, confirming dipole field depen

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’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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Electrophysiological methods

Which of the following detects changes in magnetic properties of hemoglobin?

Functional magnetic resonance imaging exploits endogenous contrast from hemoglobin oxygenation state without exogenous tracer. Deoxyhemoglobin contains four unpaired electrons in ferrous heme, making it paramagnetic, distorting local magnetic field and accelerating transverse relaxation, reducing T2* signal. Oxyhemoglobin with bound oxygen is diamagnetic and preserves homogeneity. Activation increases cerebral blood flow delivering excess oxyhemoglobin, lowering deoxyhemoglobin concentration and enhancing MRI intensity. Computed tomography relies on X-ray attenuation, EEG records voltage, PET

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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