: A cast steel core has mean length 0.4 m, cross-section 6×10⁻⁴ m², relative permeability 600. An air gap of 0.5 mm is cut in the core. Coil has 800 turns. To produce flux of 0.72 mWb in the air gap, find: a) Total reluctance b) Required current

Rohini College of Engineering offers a set of numericals covering core reluctance, air gaps, and inductance.

| Electric Circuit | Magnetic Circuit | Unit (Magnetic) | | :--- | :--- | :--- | | Electromotive Force (EMF), ( E ) (Volts) | Magnetomotive Force (MMF), ( \mathcalF = N \cdot I ) | Ampere-turns (At) | | Current, ( I ) (Amperes) | Magnetic Flux, ( \Phi ) (Webers) | Wb | | Resistance, ( R = \frac\rho lA ) | Reluctance, ( \mathcalR = \fracl\mu A ) | At/Wb | | Conductance | Permeance ( \mathcalP = 1/\mathcalR ) | Wb/At | | Ohm’s Law: ( I = E/R ) | Ohm’s Law for Magnetics: ( \Phi = \mathcalF / \mathcalR ) | — |

Problems in these PDFs typically center on the following core equations: