A pivoted aluminium bar falls much more slowly through a small region containing a magnetic field then a similar bar of an insulating material. Explain.

The system containing the rails and the wire of the previous problem is kept vertically in a uniform horizontal magnetic field B that is perpendicular to the plane of the rails. It is found that the wire stays in equilibrium. If the wire ab is replaced by another of double its mass, how long will it take in falling through a distance equal ot its length?

A rod of a magnetic material move with very small velocity v as shown in Figure below , through a uniform magnetic field . Drawn how the magnetic lines of force take shape, if the magnetic material is (i) Ferromagnetic (ii) Paramagnetic and (iii) Diamagnetic.

When a dielectric is placed in an electric field, it gets polarized. The electric field in a polarized material is less than the applied field. When a paramagnetic substance is kept in a magnetic field, the field in the substance is more than the applied field. Explain the reason of this opposite behaviour.

Long distance, competitve runners are usually small and wiry and run more slowly than sprinters, who run much shorter distances and generally have a loarger bulk of nuscles. Which of the following best explains the differences between the two types of runners?

A plane electromagnetic wave is passing through a region. Consider the quantities (a) electric field, (b) magnetic field , (c) electrical energy in a small volume and (d) magnetic energy in a small volume. Construct pairs of the quantities that oscillate with equal frequencies.

An iron needles is attracted to the ends of a bar magnet but not to the middle region of the magnet. Is the material making up the ends of a bar magnet different from that of the middle region?

A bar magnet with magnetic moment 2.5 xx10^3 J T^(-1) is rotating in horizontal plane in thespacecontaining magnetic induction B = 4xx10^(-5) T. The work done in rotating the magnet slowly from a direction parallel to the field to a direction 45^@ from the field,is (in joule)

A solenoid with large number of turns is in a closed circuit and a short bar magnet is dropped through each with its length along the axis. State the acceleration of the falling magnet when it is : a. Well above A b. At the end A c. At the middle d. At the end B e. Far away, down, from B