(I) The ability of the materials to retain the magnetism in them even magnetising field vanishes is called remanence or retentivity
(II) Hysterisis means 'lagging beyond' which one is incorrect statement ?

(I) Tendency of an object ot change its shape area and volume is called thermal expansion (ii) All natural process are reversible which one is incorrect statement ?

Answer the following question: (a) Explain qualitatively on the basis of domain picture, the irreversibility in the magnetisation curve of a ferromagnet. (b) The hysteresis loop of a soft iron piece has a much smaller area than that of a carbon steel piece. If the material is to go through repeated cycles of magnetisation, which piece will dissipate greater heat energy? (c) A system displaying a hysteresis loop such as ferromagnet is a device for strong memory? Explain the meaning of this statement. (d) What kind of ferromagnet material is used for coating magnetic tapes in a cassette player, or for building memory stores in a modern computer? (e) A certain region of space is to be shielded from magnetic fields. Suggest a method.

(I) The ratio of molar specific heat of constant pressure and constant volume of a gas is k. (II) The mean free path is inversely proportional to the pressure of the molecule too. Which one is incorrect statement?

Which of the following substances can exist in a permanently magnetised state even when the magnetic field is removed, and why? (i) Paramagnetic (ii) Ferromagnetic (iii) Ferrimagnetic

Answer the following questions a. Explain qualitatively on the basis of domain picture the irreversibility in the magnetisation curve of a ferromagnet. b. The hysteresis loop of soft iron piece has a much smaller area than that of a carbon steel piece. If the material is to go through repeated cycles of magnetisation , which piece will dissipate greater heat energy ? c. 'A system displaying a hysteresis loop such as a ferromagnet , is a device for storing memory ? ' Explain the meaning of this statement. d. What kind of ferromagnetic material is used for coating magnetic tapes in a cassette player , or for building ' memory stores ' in a modern computer ? e. A certain region of space is to be shielded from magnetic fields . Suggest a method.

A solenoid is a long helical coil of wire through which a current is runs in order to create a magnetic field. The magnetic field of the solenoid is the superposition of the fields due to the current through each coil. It is nearly uniform inside the solenoid and close to zero outside and is similar to the field of a bar magnet having a north pole at one end and a south pole at the other depending upon the direction of current flow. The magnetic field produced in the solenoid is dependent on a few factors such as, the current in the coil, number of turns per unit length etc. The following graph is obtained by a researcher while doing an experiment to see the variation of the magnetic field with respect to the current in the solenoid. The unit of magnetic field as given in the graph attached is in milli-Tesla (mT) and the current is given in Ampere. After analysing the graph, a student writes the following statements. I. The magnetic field produced by the solenoid is inversely proportional to the current I II. The magnetic field produced by the solenoid is directly proportional to the current. III. The magnetic field produced by the solenoid is directly proportional to square of the current. IV. The magnetic field produced by the solenoid is independent of the current Choose the correct statement(s).

A solenoid is a long helical coil of wire through which a current is run in order to create a magnetic field. The magnetic field of the solenoid is the superposition of the fields due to the current through each coil. It is nearly uniform inside the solenoid and close to zero outside and is similar to the field of a bar magnet having a north pole at one end and a south pole at the other depending upon the direction of current flow. The magnetic field produced in the solenoid is dependent on a few factors such as, the current in the coil, number of turns per unit length etc. The following graph is obtained by a researcher while doing an experiment to see the variation of the magnetic field with respect to the current in the solenoid. The unit of magnetic field as given in the graph attached is in milli-Tesla (mT) and the current is given in Ampere. . a straight current carrying conductor I. The magnetic field produced by the solenoid is inversely proportional to the current II. The magnetic field produced by the solenoid is directly proportional to the current. III. The magnetic field produced by the solenoid is directly proportional to square of the current. IV. The magnetic field produced by the solenoid is independent of the current. Choose from the following which of the following would be the correct statement(s).