The self inductance of an air-core inductor (solenoid) is 0.03 mH. By introducing an iron core into inductor the self-inductance increases to 30 mH. The relative permeability of the core used is

Step-by-step solution

The self-inductance of an air-core solenoid is given by L₀ = ₀ n² A l . When an iron core is introduced, the self-inductance becomes L = _ r ₀ n² A l = _ r L₀ . Given L₀ = 0.03 mH and L = 30 mH . _ r = L L₀ = 30 0.03 = 1000 = 10³ . Answer: 10³