A coil having 9 turns carrying a current produces magnetic field B₁ at the centre. Now the coil is rewounded into 3 turns carrying same current. Then, the magnetic field at the centre B₂=

Step-by-step solution

Case-I Number of turns, N₁=9 B₁= ₀ N₁ I 2 R = 9 ₀ I 2 R Case-II N₂=3 If radius of turns be R^ , then 9 2 R=3 2 R^ R^ =3 R B₂= ₀ N₂ I 2 R^ = ₀ 3 I 2 3 R = ₀ I 2 R B₂ B₁ = 2 R 9 ₀ E 2 R = 1 9 B₂= B₁ 9