MHT CET202019 Oct 2020Evening ShiftPhysicsMagnetic Properties of MatterActual
A domain in a ferromagnetic substance is in the form of a cube of side 1 m . If it contains 8 10¹⁰ atoms and each atomic dipole has a dipole moment of 9 10⁻²⁴ A / m ² , then the magnetisation of the domain is
Options
- A7 2 10⁹ Am ⁻¹
- B7 2 10⁵ Am ⁻¹
- C7 2 10¹² Am ⁻¹
- D7 2 10³ Am ⁻¹
Correct answer
B. 7 2 10⁵ Am ⁻¹
Step-by-step solution
(A) Volume of cube = ³= (10⁻⁶ )³=10⁻¹⁸ ~m ³ Total magnetic moment M =8 10¹⁰ 9 10⁻²⁴=72 10⁻¹⁴ ~A - m ² Magnitization = M V = 72 10⁻¹⁴ 10⁻¹⁸ =7.2 10⁵ ~A / m