Key Idea : Inductance of a coil is numerically equal to the emf induced in the coil when the current in the coil changes at the rate of 1As−1. If I is the current flowing in the circuit, then flux linked with the circuit is observed to be proportional to I, ie, ϕ∝Ior ϕ=LI where L is called the self-inductance or coefficient of self-inductance or simply inductance of the coil. Net flux through solenoid, ϕ=500×4×10−3=2 Wb or 2=L×2 [after putting values in Eq. or L=1H