Balbharati solutions for Physics [English] 12 Standard HSC Maharashtra State Board chapter 11 - Magnetic Materials [Latest edition]

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Intensity of the magnetic field of the earth at the point inside a hollow iron box is ______.

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Soft iron is used to make the core of the transformer because of its ______.

Which of the following statements is correct for diamagnetic materials?

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A rectangular magnet suspended freely has a period of oscillation equal to T. Now it is broken into two equal halves (each having half of the original length) and one piece is made to oscillate freely. Its period of oscillation is T′, the ratio of T′/T is ______.

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A magnetising field of 360 Am⁻¹ produces a magnetic flux density (B) = 0.6T in a ferromagnetic material. What is its permeability in Tm A⁻¹?

Which property of soft iron makes it useful for preparing electromagnet?

What happens to a ferromagnetic material when its temperature increases above curie temperature?

What should be retentivity and coercivity of permanent magnet?

Answer in brief.

Discuss the Curie law for paramagnetic material.

Obtain an expression for the orbital magnetic moment of an electron rotating about the nucleus in an atom.

Answer in brief.

What does the hysteresis loop represent?

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Explain one application of electromagnet.

When a plate of magnetic material of size 10 cm × 0.5 cm × 0.2 cm (length, breath, and thickness respectively) is located in a magnetizing field of 0.5 × 10⁴ A/m^-1, then a magnetic moment of 0.5 Am² is induced in it. Find the magnetic induction in the plate.

A rod of magnetic material of cross-section 0.25 cm² is placed in a magnetizing field of intensity 4000 A/m^-1. The magnetic flux passing through the rod is 25 × 10^-6 Wb. Find out

(a) relative permeability

(b) magnetic susceptibility and 

(c) magnetisation of the rod.

The work done for rotating a magnet with magnetic dipole moment m, through 90° from its magnetic meridian is n times the work done to rotate it through 60°. Find the value of n.

An electron in an atom is revolving around the nucleus in a circular orbit of a radius of 5.3 x 10^-11 m, with a speed of 2 x 10⁶ m/s. Find the resultant orbital magnetic moment and angular momentum of the electron. [e = 1.6 x 10^-19 C, m_e= 9.1 x 10^-31 kg]

A paramagnetic gas has 2.0 × 10²⁶ atoms/m with atomic magnetic dipole moment of 1.5 × 10⁻²³ A m² each. The gas is at 27°C.

1. Find the maximum magnetization intensity of this sample.
2. If the gas in this problem is kept in a uniform magnetic field of 3 T, is it possible to achieve saturation magnetization? Why?

A magnetic needle placed in uniform magnetic field has magnetic moment of 2 x 10^-2 A·m², and a moment of inertia of 7 .2 x 10^-7 kg·m². It performs 10 complete oscillations in 6 s. What is the magnitude of the magnetic field?

A short bar magnet is placed in an external magnetic field of 700 gauss. When its axis makes an angle of 30° with the external magnetic field, it experiences a torque of 0.014 Nm. Find the magnetic moment of the magnet, and the work done in moving it from its most stable to the most unstable position.

A magnetic needle is suspended freely so that it can rotate freely in the magnetic meridian. In order to keep it horizontal position, a weight of 0.2 g is kept on one end of the needle. If the pole strength of the needle is 20 Am, find the value of the vertical component of the Earth's magnetic field. (g = 9.8 ms^-2)

The susceptibility of a paramagnetic material is χ at 27° C. At what temperature its susceptibility be χ/3?