What must be checked before using the Voltage divider relation?

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

2. Resistive networks

Voltage divider

Formula

V_o=V_i\frac{R_2}{R_1+R_2}

Detail

Shows Vo vs R2 on the unloaded voltage divider: Vo is the fraction R2/(R1+R2) of Vi.

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

Worked example

With

V_i=12\,\mathrm V

R_1=2\,\mathrm{k\Omega}

and

R_2=1\,\mathrm{k\Omega}

V_o=12(1/3)=4\,\mathrm V

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 Voltage divider relation?: Check a resistive DC network, sign references and whether the divider is loaded.

Also known as

voltage divider
voltage-divider formula

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

Voltage divider

In 2. Resistive networks

Formula

V_o=V_i\frac{R_2}{R_1+R_2}

Detail

Shows Vo vs R2 on the unloaded voltage divider: Vo is the fraction R2/(R1+R2) of Vi.

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

Worked example

With

V_i=12\,\mathrm V

R_1=2\,\mathrm{k\Omega}

and

R_2=1\,\mathrm{k\Omega}

V_o=12(1/3)=4\,\mathrm V

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 Voltage divider relation?: Check a resistive DC network, sign references and whether the divider is loaded.

Also known as

voltage divider
voltage-divider formula

Conventions

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

Last reviewed: 2026-09-19

Found an error? Contact us.

Voltage divider

Tags

Detail

Explore the idea

Variables

Conditions

Intuitive explanation

Worked example

Common mistakes

Frequently asked questions

Also known as

Related topics

Conventions

Related formulas

Voltage divider

Tags

Detail

Explore the idea

Variables

Conditions

Intuitive explanation

Worked example

Common mistakes

Frequently asked questions

Also known as

Related topics

Conventions

Related formulas