What must be checked before using the Thévenin resistance relation?

Check a resistive DC network, sign references and whether the divider is loaded.

2. Resistive networks

Thévenin resistance

Formula

R_{\mathrm{Th}}=\frac{V_{\mathrm{prueba}}}{I_{\mathrm{prueba}}}

Detail

RTh is the resistance seen at the terminals with independent sources killed.

Explore the idea

Variables

$V_i,V_o$ voltages (V)
$R_1,R_2,R_L,R_{\mathrm{Th}}$ resistances (Ω)
$I_T,I_N$ currents (A).

Conditions

Linear resistive DC network; unloaded divider unless RL is stated.

Intuitive explanation

For “Thévenin resistance”: the divider and Thévenin/Norton reduce the network to one port; a load across R2 lowers Vo.

Worked example

If a test source of

1\,\mathrm V

produces

0.5\,\mathrm{mA}

R_{\mathrm{Th}}=1/0.0005=2\,\mathrm{k\Omega}

Common mistakes

forgetting that RL sits in parallel with R2
using the unloaded divider with a load present
mixing kΩ with Ω

Frequently asked questions

What must be checked before using the Thévenin resistance relation?: Check a resistive DC network, sign references and whether the divider is loaded.

Also known as

voltage divider, current divider, Thévenin, Norton

Conventions

V, A or Ω according to the left-hand side

Last reviewed: 2026-09-19

Found an error? Contact us.

Related formulas

2. Resistive networks

Thévenin resistance

In 2. Resistive networks

Formula

R_{\mathrm{Th}}=\frac{V_{\mathrm{prueba}}}{I_{\mathrm{prueba}}}

Detail

RTh is the resistance seen at the terminals with independent sources killed.

Explore the idea

Variables

$V_i,V_o$ voltages (V)
$R_1,R_2,R_L,R_{\mathrm{Th}}$ resistances (Ω)
$I_T,I_N$ currents (A).

Conditions

Linear resistive DC network; unloaded divider unless RL is stated.

Intuitive explanation

For “Thévenin resistance”: the divider and Thévenin/Norton reduce the network to one port; a load across R2 lowers Vo.

Worked example

If a test source of

1\,\mathrm V

produces

0.5\,\mathrm{mA}

R_{\mathrm{Th}}=1/0.0005=2\,\mathrm{k\Omega}

Common mistakes

forgetting that RL sits in parallel with R2
using the unloaded divider with a load present
mixing kΩ with Ω

Frequently asked questions

What must be checked before using the Thévenin resistance relation?: Check a resistive DC network, sign references and whether the divider is loaded.

Also known as

voltage divider, current divider, Thévenin, Norton

Conventions

V, A or Ω according to the left-hand side

Last reviewed: 2026-09-19

Found an error? Contact us.

Thévenin resistance

Tags

Detail

Explore the idea

Variables

Conditions

Intuitive explanation

Worked example

Common mistakes

Frequently asked questions

Also known as

Related topics

Conventions

Related formulas

Thévenin resistance

Tags

Detail

Explore the idea

Variables

Conditions

Intuitive explanation

Worked example

Common mistakes

Frequently asked questions

Also known as

Related topics

Conventions

Related formulas