ELC-48

Ampere-turn

Magnetomotive force.

Reading speed

CircuitsAmpere-turn

Governing equation

\mathcal{F}=NI

$I \in \left[0.1, 20\right]$

where

N: Turns (—)
I: Current (A)
mathcal{F}: MMF (A)

The figure, part by part

Each numbered marker wears the color of its card. Hover a card to light the marker. Tap a marker to jump to that card. The slider walks a red point along the curve; Animate drawing traces it like a pen.

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①

Governing law — red

\mathcal{F}=NI

$I \in \left[0.1, 20\right]$

$I = 0.1$ $mathcal{F} = 20$

Along the curve

②

Domain of the variable — blue

I_{\min} = 0.1,\quad I_{\max} = 20

$I \in \left[0.1, 20\right]$

$I = 0.1$ $I = 0.1$

Along the curve

③

Response curve — green

\mathcal{F}=NI

$I \in \left[0.1, 20\right]$

$I = 0.1$ $mathcal{F} = 20$

Along the curve

④

Rate of change — amber

\frac{\mathrm{d}mathcal{F}}{\mathrm{d}I}

$I \in \left[0.1, 20\right]$

$I = 0.225$ $mathcal{F}^{\prime} = 200$

Along the curve

Lecture brief

Historical brief

Ohm (1827), Kirchhoff (1845) and Maxwell’s circuit reduction still run every board: RLC transients, transformers, skin effect and three-phase power. The sheets are those network laws, not a SPICE deck. This sheet (ELC-48 — Ampere-turn) is the form associated with Ampere-turn. Working symbols: $N$ , $I$ $\rightarrow$ $mathcal{F}$ . Magnetomotive force. Pedagogical SI sheet with a live model and a swept parameter.

Purpose

Purpose: compute

mathcal{F}

from

N

I

in Electrical via

\mathcal{F}=NI

Magnetomotive force. Use it when a real electrical question must be answered in SI before a code check.

Live realistic example

In symbols

Live case. Given

N = 200.000\,\mathrm{—}

I = 2.000\,\mathrm{A}

, the governing relation

\mathcal{F}=NI

yields

mathcal{F} = 400.0\,\mathrm{A}

. One governing identity, SI units, a single sweep on the sheet. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

Turns N200 —Current I2 A

Outputs

MMF mathcal{F}400.0 A

Reading speed

Watch on YouTube

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Narration of this film

One governing identity, SI units, a single sweep on the sheet.

Magnetomotive force. Pedagogical SI sheet with a live model and a swept parameter.

Reading speed

Watch on YouTube