Two points A and B are situated at distance x and 2 x respectively from the nearer pole of a magnet 2 cm long. The ratio of magnetic field at A and B is

Step-by-step solution

For a magnet B= ₀ 4 2 M r^3 (nearly) array lc & B₂ B₁ = ( r₁ r₂ )^3 & B₂ B₁ = ( x 2 x )^3 B₂ B₁ = 1 8 array Thus, B₁: B₂=8: 1 approximately