A solenoid 2.00 m long has 2000 loops and carries 1600 A. What is the field strength inside it?

1. Use B = mu0 n I, where n is loops per unit length. 2. Find n first: n = 2000 loops / 2.00 m = 1000 per metre. 3. Substitute: B = (4 pi x 10^-7 T m/A)(1000 per m)(1600 A). 4. Multiply the last two factors: (1000)(1600) = 1.6 x 10^6 A per m. 5. Then B = (4 pi x 10^-7)(1.6 x 10^6) = 4 pi x 0.16 T. 6. Evaluating gives B = 2.01 T. 7. A current this large through 1000 loops in a metre would cause serious heating, which is why such coils are made superconducting. 8. An answer of 20.1 T comes from taking n as 10 per centimetre and then forgetting to convert it to per metre. _Source: OpenStax College Physics (CC BY 4.0), Ch 22 "Magnetism", section 22.9 Magnetic Fields Produced by Currents: Ampere's Law_