Horizontal magnetic field of earth at Mumbai is 1.5 × 10⁻⁴ T in North direction. A small bar magnet of magnetic moment 10 Am² is kept on a horizontal table such that its North pole points due North. What is the magnetic field at 10 cm from centre of magnet at a point on its axis due North of it :-
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Question

Horizontal magnetic field of earth at Mumbai is 1.5 × 10⁻⁴ T in North direction. A small bar magnet of magnetic moment 10 Am² is kept on a horizontal table such that its North pole points due North. What is the magnetic field at 10 cm from centre of magnet at a point on its axis due North of it :-

Options

G1 Physics · Accepted Answer

The axial field of the magnet at 0.10 m is B from magnet = μ₀(2M)/(4πr³)=2×10⁻³ T. It points north and adds to Earth's 1.5×10⁻⁴ T. Total field =2.15×10⁻³ T, option C.