question_answer 33)

  A long solenoid has 1000 turns per metre and carries a current of 1 A. It has a soft iron core of = 1000. The core is heated beyond the Curie temperature, . The field in the solenoid is (nearly) un-changed but the  field decreases drastically The and  fields in the solenoid are nearly unchanged The magnetisation in the core reverses direction The magnetisation in the core diminishes by a factor of about

Answer:

  (a,d)In the solenoid, H = n = a constant and changes due to variation in . When temperature of the iron core of solenoid (which is ferromagnetic material) is raised beyond curie temperature, then soft iron core behaves as para magnetic material. We know that Thus magnetisation of the core diminishes by a factor . Hence, options (a) and (d) are correct.