A small current loop can be used as a compass. When it\'s placed in an external
ID: 1550201 • Letter: A
Question
A small current loop can be used as a compass. When it's placed in an external magnetic field, (a) which plane will it be rotated into, and how will the direction of its magnetic dipole moment Mu compare to that of B? (b) Will the loop then be stretched or compressed by B? (c) If B is spatially uniform, will it exert a net force on the loop as a whole (if so, in which direction)? (d) If B varies with position, will the force on the loop be directed toward positions where B is greater or less? (e) When a charged particle orbits in a magnetic field (see Ex 27-7, pg 715), its magnetic dipole moment is antiparallel to B. The force on the orbiting particle is inward (centripetal), but on the wire loop it must be outward tor stability-explain.Explanation / Answer
(a) when we keep carrent carrying coil in magnetic field , it will experience a torque .The torque actinv on coil will be zero if and only if plane of coil is perlendicular to direction of magnetic field. For maximum tkrque plane of coil must be parallel to magnetic field.Coil will ratate in perpendicular direction of its plane.
(b) Loop will only rotate due to torque , it will niether strech not compress.
(c) when B is uniform then total force on loop is zero but non zero torque acts on it.
(d) When B varies with position then B is non uniform , due to non uniform magnetic field forces of different magnitute act on loop and it will move where stength of field is high.
(e). since in every atom electrons revolves around nucleus , the orbital and spin motion of electron generates magnetic moment in atom, during orbital motion magnetic force acts on Electrons in outward direction in krder to bind them in the circular orbit centripetel force acts on them to maintain constant orbital motion.In cas of current carryinv coil according tl flemings left hand rule magnetic force acts on it in outward direction to maintain constant structure and area of loop, cause magnetic field due to loop depends on radius.