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To convert from Ampere-turns (A·t) to Gilberts (Gi), you use the conversion factor that 1 Gilbert is approximately 0.79577 A·t. Therefore, to convert A·t to Gi, you divide by this factor.
Example:
Convert an MMF of 100 A·t to Gilberts.
100 A·t / 0.79577 ≈ 125.66 Gi
Answer: 100 Ampere-turns is equal to approximately 125.66 Gilberts.
Magnetomotive force, or MMF, is the property in a magnetic circuit that produces a magnetic field. It is the magnetic analogue of electromotive force (EMF) or voltage in an electrical circuit. Just as voltage is the 'pressure' that drives an electric current through a resistance, magnetomotive force is the 'pressure' that drives magnetic flux through a magnetic reluctance. MMF is the phenomenon that gives rise to a magnetic field. In most practical applications, this force is generated by passing an electric current through a coil of wire.
The strength of the magnetomotive force is directly proportional to both the number of turns of wire in the coil and the magnitude of the electric current flowing through it. Doubling the current or doubling the number of turns in the coil will double the MMF. This principle is the foundation of all electromagnets, from small relays in electronic circuits to the massive superconducting magnets used in MRI machines and particle accelerators. Understanding MMF is essential for engineers and physicists who design and analyze magnetic circuits, transformers, electric motors, and other electromagnetic devices. The standard unit is the Ampere-turn, which directly reflects how MMF is created.
Fₘ = NI, where 'N' is the number of turns of wire in the coil and 'I' is the electric current in Amperes.Fₘ = ΦRₘ. This is analogous to Ohm's Law (V = IR).Fₘ = ∮ H ⋅ dl. This is a more general statement of Ampere's Law.For an inductor or electromagnet coil, the MMF is simply the product of the electric current flowing through the coil and the number of turns of wire in the coil. For example, a 100-turn coil with 2 Amperes of current produces a magnetomotive force of 200 Ampere-turns.
No, they are related but distinct. MMF is the overall 'driving force' for the entire magnetic circuit. Magnetic field strength (H-field) is the intensity of the magnetizing force at a specific point in space, essentially the MMF per unit length.
Magnetic reluctance is the magnetic equivalent of electrical resistance. It is a measure of the opposition to the formation of a magnetic field within a material. An air gap in a magnetic circuit has high reluctance, while a soft iron core has low reluctance.
MMF is the direct measure of the strength of an electromagnet. To create a stronger electromagnet, you can either increase the current flowing through its coil or increase the number of turns in the coil. Both actions increase the magnetomotive force.
William Gilbert was an English physician and scientist in the late 16th and early 17th centuries. He is often called the 'father of magnetism' for his pioneering 1600 publication 'De Magnete', in which he described his experiments with magnetism and proposed that the Earth itself was a giant magnet. The CGS unit of MMF is named in his honor.