AP EAMCET202022 Sep 2020Morning ShiftPhysicsMagnetic Properties of MatterActual
90. If the dipole moment of a short bar magnet is 1.25 ~A - m ^2 , find the magnetic field on its axis at a distance of 0.5 ~m from the centre of the magnet.
Options
- A1.0 10⁻⁴ NA ⁻¹ ~m ⁻¹
- B4.0 10⁻² NA ⁻¹ ~m ⁻¹
- C2.0 10⁻⁶ NA ⁻¹ ~m ⁻¹
- D6.64 10⁻⁸ NA ⁻¹ ~m ⁻¹
Correct answer
C. 2.0 10⁻⁶ NA ⁻¹ ~m ⁻¹
Step-by-step solution
Dipole moment, aligned M & =1.25 ~A - m ^2 r & =0.5 ~m aligned Magnetic field on the axial position of bar magnet is given as aligned B & = ₀ 4 2 M r^3 =10⁻⁷ 2 1.25 (0.5)^3 & =10⁻⁷ 2 1.25 0.125 =2 10⁻⁶ NA ⁻¹ ~m ⁻¹ aligned