Question

Two points A and B are located at a distances 20cm and 30cm from the centre of a short bar magnet on its axial line. The ratio of magnetic induction at A and B is

Answer 1

$\huge\mathcal{\underline{\color{purple}Answer}}$

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⇒ $B_{axial}=$$\frac{μ₀}{4π}\frac{2M}{d^3}$

⇒ $B_{axial}$ ∝ $\frac{1}{d^3}$

⇒ $\frac{B_{ at A} }{B_{at B} }=\frac{d^2_{B} }{d^2_{A}}=\frac{30 cm^3}{20 cm^3}$

⇒ $\frac{27}{8}$

☆Hence, The ratio of magnetic induction at A and B is $27:8$

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Hope it Helps !!!