12. The dipole moment associated with an atom of iron in an iron bar is 1.8 x 10-23 amp-m?. Assume that all the atoms in the bar which is 5 cm long and has a cross- sectional area of 1 cm². have their dipole moments aligned. (a) What is the dipole moment of the bar? (b) What torque must be exerted to hold this magnet at right angles to the external field of 1.5 T? The density of iron is 7.9 gm/em. The atomic mass of iron is 55.8 grams/mole 1mole = 6.02 x 1023 atoms

12. The dipole moment associated with an atom of iron in an iron bar is 1.8 x 10-23 amp-m?. Assume that all the atoms in the bar which is 5 cm long and has a cross- sectional area of 1 cm². have their dipole moments aligned. (a) What is the dipole moment of the bar? (b) What torque must be exerted to hold this magnet at right angles to the external field of 1.5 T? The density of iron is 7.9 gm/em. The atomic mass of iron is 55.8 grams/mole 1mole = 6.02 x 1023 atoms