Two short magnets of magnetic moment 2 Am² and 5 Am² respectively are placed along two lines drawn at right angle to each other on the sheet of paper as shown in the figure. What is the magnetic field at the point of intersection of their axis:

Question

G1 Physics · Accepted Answer

Use the axial dipole field B axial=μ₀(2M)/(4πr³) and equatorial field B equatorial=μ₀M/(4πr³). The two contributions at the intersection are perpendicular for the shown magnets. Substitution of M₁=2 A·m², r₁=0.3 m, M₂=5 A·m², r₂=0.4 m gives resultant ≈2.15×10⁻⁵ T. Hence A.