NEET2016PhysicsMagnetic Effects of CurrentActual
A long wire carrying a steady current is bent into a circular loop of one turn. The magnetic field at the centre of the loop is B . It is then bent into a circular coil of n turns. The magnetic field at the centre of this coil of n turns will be
Options
- An B
- Bn 2 B
- C2 n B
- D2 n 2 B
Correct answer
B. n 2 B
Step-by-step solution
B = μ 0 I 2 r . When n turns are made, radius becomes r ′ . n × 2 π r ′ = 2 π r ⇒ r ′ = r n . Now, B ′ = μ 0 n I 2 r ′ = n 2 μ 0 I 2 r = n 2 B .