Maxwell’s equations have been briefly covered from view point of understanding electrical machines. Simple magnetic circuits along with the Maxwell’s equations, concepts of MMF, magnetic flux and flux density, reluctance, permeance, leakage flux, fringing, saturation, measurement of AC/DC flux density, Hall effect devices, and their use in electrical machines. Permanent magnets, magnetic lines of forces, normal force and its use in hyperloop system of transport, relative permeability of iron, Ampere’s law applied to an ideal magnetic circuit, analogy between electric and magnetic circuits, magnetic circuit with air-gap, application of Ampere’s critical law, losses in magnetic circuits—hysteresis and eddy current, concept of power flow, energy and co-energy, stored energy and forces, λ-I diagram for single excited system, open magnetic circuit and energy in multi-excited system have been dealt.