Magnetism and Matter
17 Board Physics previous year questions on Magnetism and Matter — options free on every question; 2 include the answer & explanation free, the rest unlock with PYQ Pass.
The magnetic moment of an iron bar is \(\mathrm{M}\). It is now bent in such a way that it forms an arc section of a circle subtending an angle of \(60^\circ\) at the centre. The magnetic moment of this arc section is :
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\(\frac{3\mathrm{M}}{\pi }\)
- Arc Length = L = Rθ (θ=π/3). Chord Length L' = 2Rsin(θ/2) = 2Rsin(π/6) = R. Since R = L/θ = 3L/π, the new magnetic length is L' = 3L/π.
- New Moment M' = m × L' = m × (3L/π). Substitute m = M/L. M' = (M/L) × (3L/π) = 3M/π.
(NEW NCERT 12th Page No. 137, 138)
Which of the following substances has relative magnetic permeability \({\mu }_{\mathrm{r}}≫1\) ?
Nickel
Relative magnetic permeability (\(\mu_r\)) is a measure of how much a material can become magnetized in an applied magnetic field compared to vacuum. When \(\mu_r \gg 1\), it indicates that the material is highly magnetic, typically found in ferromagnetic materials. Examples of substances with \(\mu_r \gg 1\) include iron, cobalt, and nickel.
The magnetic potential energy, when a magnetic bar of magnetic moment \(\vec{\mathrm{m}}\) is placed perpendicular to the magnetic field \(\vec{B}\) is :
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The magnetic susceptibility for a diamagnetic material is
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Which of the following substances has relative magnetic permeability \({\mu }_{\mathrm{r}}≫1\) ?
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The magnetic susceptibility for a diamagnetic material is
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Which of the following pairs is that of paramagnetic materials?
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Which of the following substances has relative magnetic permeability \({\mu }_{\mathrm{r}}≫1\) ?
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Which of the following pairs is that of paramagnetic materials?
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Which of the following pairs is that of paramagnetic materials?
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Which of the following substances has relative magnetic permeability \({\mu }_{\mathrm{r}}≫1\) ?
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The magnetic susceptibility for a diamagnetic material is
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If a bar magnet is cut into two equal pieces transverse to its length, then each piece will
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Assertion (A): When a bar of copper is placed in an external magnetic field, the field lines get concentrated inside the bar.
Reason \((R)\) : Copper is a paramagnetic substance.
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Which of the following has its permeability less than that of free space ?
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A diamagnetic substance is brought near the north or south pole of a bar magnet. It will be :
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Assertion (A) : Diamagnetic substances exhibit magnetism.
Reason (R) : Diamagnetic materials do not have permanent magnetic dipole moment.
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