A solenoid of length and uniform cross-sectional area has tightly wound turns and is…

PHYSICS · Multi-part · AP · Physics C: Electricity and Magnetism · Electromagnetic Induction · Electromagnetic Induction

Problem

A solenoid of length ℓ\ell and uniform cross-sectional area AA has NN tightly wound turns and is air-cored. (i) Starting with the expression for the magnetic field inside the solenoid, derive a formula for its self-inductance LL in terms of μ0, N, A\mu_0,\,N,\,A and ℓ\ell. (ii) A solenoid 0.40 m0.40\,\text{m} long with radius 2.0 cm2.0\,\text{cm} has 20002000 turns. Calculate its inductance for an air core. (iii) The solenoid is now completely filled with a material of relative permeability μr=100\mu_r=100. Find the new inductance and determine the ratio of the magnetic energy stored in the solenoid for a current of 1.0 A1.0\,\text{A} with and without the core.

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