(a) Magnetic field lines show the directions (at every point) which a small magnetised
Channel: Doubtnut
Date: 2020-08-02

(a) Magnetic field lines show the directions (at every point) which a small magnetised needle takes up (at that point). Do the magnetic field lines also represent the lines of force of a moving charged particle at every point?  (b) Magnetic field lines can be entirely confined within the core of a toroid, but not within a straight solenoid. Why?  (c) If magnetic monopoles existed, how would Gauss's law of magnetism be modified?  (d) Does a bar magnet exert a torque on itself due to its own field? Does one element of a current carrying wire exert a force on another element of the same wire?  (e) Magnetic field arises due to charges in motion. Can a system have magnetic moment even though its net charge is zero?  (f) Magnetic force is always normal to the velocity of a charge and therefore does no work. An iron nail held near a magnet, when released, increases its kinetic energy as it moves to cling to the magnet. What agency is responsible for this increase in kinetic energy if not the magnetic field?