Earth के पास magnetic field होने से क्या लाभ है | facts about space | information about solar system

In a conductor, there are free electrons which continuously move randomly but inside the volume of the conductor. When such a conductor is placed inside a magnetic field then what can you say about the magnetic forces acting on the system?

Find approximately the third cosmic velocity v_3 , i.e. the minimum velocity that has to be imparted to a body relative to the Earth's surface to drive it out of the Solar system. The rotation of the Earth about its own axis is to be neglected.

A magnet is suspended horizontal in the earth's magnetic field. When it is displaced and then released it oscillates in a horizontal plane with a period T. If a place of wood of the same moment of inertia (about the axis of rotation) as the magnet is attached to the magnet what would the new period of oscillation of the system become?

A coil wire rotates about a horizontal north-south axis with its plane kept along axis. Assume that at the point, the earth's magnetic field is along north direction. How does the magnetic field contribute to the emf induced in this coil?

A bar magnet of magnetic moment 2.0 A m^2 is free to rotate about a vertical axis through its centre. The magnet is released from rest from the east-west position. Find the kinetic energy of the magnet as it takes the north-south position. The horizontal component of the earth's magnetic field is B = 25 muT .

Answer the following questions: (a) The earth's magnetic field varies from point to point in space. Does is also change with time? If so, on what time scale does it change appreciably? (b) The earth's core is known to contain iron. Yet geologists do not regard this as a source of earth's magnetism, why? (c) The charged currents in the outer conducting regions of earth's core are thought to be possible for earth's magnetism. What might be the battery to sustain these currents? (d) The earth may have even reversed the direction of its field several times during its history of 4 to 5 billion years. How can geologist know about the earth's field in such distant past? (e) The earth's field departs from its dipole shape substantially at large distances (greater than about 30000km). What agencies may be responsible for this distortion? (f) Interstellar space has an extremely weak magnetic field of the order of 10^(-12)T . Can such a weak field be of any significant consequence? Explain.