Resistive voltage dividers
Voltage or current dividers

In their elementary form, resistive voltage dividers have :

• an input resistor R₀ = R₁ + R₂ which we will assume to be constant ;

• a reduction ratio a = R₂ /R₀ .

The equivalent diagram deduced from Thévenin's theorem consists of a source of electromotive force aU (U being the voltage actually applied to the divider) and internal resistance :

This internal resistance is also expressed by aR₁ and a (1 – a )R₀ . The internal resistance is maximum for a = 1/ 2 and is then worth R₀...