A magnetic needle is kept in a non-uniform magnetic field. It experiences
(A) a force and a torque
(B) a torque but not a force
(C) neither a force nor a torque
(D) a force but not a torque

Force and torque

(a) What happens if a bar magnet is cut into two pieces (i) transverse to its length (ii) along its length? (b) What happens if an iron bar magnet is melted? Does it retain its magnetism? (c) A magnetised needle in a uniform magnetic field experiences a torque but no net force. However, an iron nail near a bar magnet experiences a force of attration in addition to a torque, explain. (d) Must every magnetic field configuration have a north pole and a south pole? What about the field due to a toroid? (e) Can you think of magnetic field configuration with three poles? (f) Two identical looking iron bars A and B are given, one of which is definitely known to be magnetised. How would one ascertain whether or not both are magnetised? If only one is magnetised how does one ascertain which one? Use nothing else but the bars A and B.

Assertion (A): A magnetic suspended freely in an uniform magnetic field experiences no net force, but a torque that tends to align the magnet along the field when it is deflected form equilibrium position Reason (R ): Net force mB-mB=0 , but the forces on north and south poles being equal, unlike and parallel make up a couple that tends to align the magnet, along the field.

Torque acting on a current loop in a uniform magnetic field is equal to

In Fig., find the resultant magnetic force and torque about C.

If plane of coil and uniform magnetic field B(4T0 is same then torque on the current carrying coil is

A current carrying loop is placed in a uniform magnetic field. The torque acting on it does not depend upon

Find the resultant magnetic force and torque on the loop.

Assertion: When a magnetic dipole is placed in a non-uniform magnetic field, only a torque acts on the dipole. Reason: Force would also acts on dipole if magnetic field were uniform.

Classify the tasks shown below into examples of force and torque .