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#magnetic properties

9 public questions tagged with this topic.

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 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 > Magnetic Field Lines, Bar Magnet and Dipole Moment

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 senses positron decay, none sense magnetic properties of hemoglobin differently.

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.