ELC-39

Thévenin load current

Load current of the Thévenin equivalent.

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CircuitsThévenin load current

Governing equation

I_L=V_{oc}/(R_{th}+R_L)

$R_L \in \left[0.1, 80\right]$

where

V_{oc}: Open-circuit (V)
R_{th}: Rth (Ω)
R_L: Load (Ω)
I_L: Load current (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

I_L=V_{oc}/(R_{th}+R_L)

$R_L \in \left[0.1, 80\right]$

$R_L = 0.1$ $I_L = 2.927$

Along the curve

②

Domain of the variable — blue

R_L_{\min} = 0.1,\quad R_L_{\max} = 80

$R_L \in \left[0.1, 80\right]$

$R_L = 0.1$ $R_L = 0.1$

Along the curve

③

Response curve — green

I_L=V_{oc}/(R_{th}+R_L)

$R_L \in \left[0.1, 80\right]$

$R_L = 0.1$ $I_L = 2.927$

Along the curve

④

Rate of change — amber

\frac{\mathrm{d}I_L}{\mathrm{d}R_L}

$R_L \in \left[0.1, 80\right]$

$R_L = 0.603$ $I_L^{\prime} = -0.573$

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-39 — Thévenin load current) is the form associated with Thévenin load current. Working symbols: $V_{oc}$ , $R_{th}$ , $R_L$ $\rightarrow$ $I_L$ . Load current of the Thévenin equivalent. Pedagogical SI sheet with a live model and a swept parameter.

Purpose

Purpose: compute

I_L

from

V_{oc}

R_{th}

R_L

in Electrical via

I_L=V_{oc}/(R_{th}+R_L)

Load current of the Thévenin equivalent. Use it when a real electrical question must be answered in SI before a code check.

Live realistic example

In symbols

Live case. Given

V_{oc} = 12.000\,\mathrm{V}

R_{th} = 4.000\,\mathrm{Ω}

R_L = 8.000\,\mathrm{Ω}

, the governing relation

I_L=V_{oc}/(R_{th}+R_L)

yields

I_L = 1.000\,\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

Open-circuit V_{oc}12 VRth R_{th}4 ΩLoad R_L8 Ω

Outputs

Load current I_L1.000 A

Reading speed

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Narration of this film

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

Load current of the Thévenin equivalent. Pedagogical SI sheet with a live model and a swept parameter.

Reading speed

Watch on YouTube