Obviously, if there wasn't a gap, the rotor would not be able to rotate! However, the gap should be as small as possible in order to minimise the reluctance of the magnetic circuit (reluctance is equivalent to resistance), because the reluctance of air is very much larger than for silicon steel.
The core, together with the machine's air gaps, form what is known as a 'magnetic circuit', which is a low-reluctance path that encloses the magnetic flux produced by its field windings, in order to concentrate that flux in the air gap through which the armature passes.
It isn't. However, the ratio of magnetomotive force to magnetic flux will tell you what the reluctance happens to be for that particular ratio, in exactly the same way that resistance isn't dependent on current, but the ratio of voltage to current will tell us what the resistance happens to be for that particular ratio.
Magnetomotive force (not 'magneticmotive force') is analogous to electromotive force, in the same way that magnetic flux is analogous to current, and reluctance is analogous to resistance. Mmf, flux, and reluctance also have the same 'Ohm's law' relationship as emf, current, and resistance. It is mmf that sets up the magnetic flux; it is the emf that sets up the current.One point worth noting is that despite mmf being measured in amperes (the product of the current flowing through a coil and the number of turns), it is still analogous to emf, and not current!
E = IxR where E is Electromotive force measure in VoltsI = current flow measured in AmperesR = total resistance in the circuit.Volts and Amperes are named for people, so are capitalized.AnswerWhat is generally (but incorrectly) called the "Ohm's Law" equation for a magnetic circuit is as follows:magnetomotive force = flux x reluctanceMagnetomotive force (equivalent to emf in an electric circuit) is measured in amperes (but often spoken as 'ampere turns'), flux (equivalent to current in an electric circuit) is measured in webers (pronounced 'vay-bers'), and reluctance (equivalent to resistance in an electric circuit) is measured in amperes per weber (but often spoken as 'ampere turns per weber').
Reluctance is the opposition offered by a magnetic circuit to the formation of magnetic flux. The symbol for reluctance is R or Rm. Reluctance is measured in amperes per weber (A/Wb). Reluctance is equivalent to resistance in an electric circuit.
Magnetic reluctance is a concept used in the analysis of magnetic circuits. The term was coined in May 1888. There are several methods to determine the magnetic characteristics.
Reluctance is the opposition offered by a magnetic circuit to the formation of magnetic flux. It is equivalent to resistance in an electric circuit.Reluctance is the ratio of a magnetic circuit's magnetomotive force (measured in amperes) to its magnetic flux(measured in webers, pronounced 'vay-bers'). So, reluctance is measured in amperes per weber (which is often 'spoken' as 'ampere-turns per weber'). This is equivalent, in an electric circuit, to the ratio: electomotive force to electric current.
Resistance to movement of magnetic lines of force is described as reluctance. Reluctance is similar to resistance in an electric circuit and is a measure of the opposition that a magnetic circuit offers to the magnetic flux. It depends on the material and the geometry of the magnetic circuit.
The reluctance symbol is a measure of the opposition to magnetic flux in a magnetic circuit. It is represented by the symbol "R" and is the reciprocal of permeance, which is a measure of the ease with which magnetic flux is established in a material or circuit.
Reluctance torque is the torque generated in a reluctance motor due to the tendency of the rotor to align itself with the stator magnetic field. It occurs as a result of the variation in reluctance in the magnetic path between the rotor and stator. This torque is responsible for the motion of the motor and is one of the main torque components in reluctance motor operation.
Obviously, if there wasn't a gap, the rotor would not be able to rotate! However, the gap should be as small as possible in order to minimise the reluctance of the magnetic circuit (reluctance is equivalent to resistance), because the reluctance of air is very much larger than for silicon steel.
reluctance, it is the resistance of a magnetic circuit to the establishment of a magnetic flux by a magnetomotive force.
reluctance
The resistance of a substance to the passing of magnetic flux lines is called magnetic reluctance. It is analogous to electrical resistance in a circuit and is influenced by the material's properties and geometry. A material with high reluctance impedes the flow of magnetic flux lines, while one with low reluctance allows them to pass more easily.
Magnetic reluctance is a concept used in the analysis of magnetic circuits. The term was coined in May 1888. There are several methods to determine the magnetic characteristics.
The core, together with the machine's air gaps, form what is known as a 'magnetic circuit', which is a low-reluctance path that encloses the magnetic flux produced by its field windings, in order to concentrate that flux in the air gap through which the armature passes.