Unloaded Voltage Divider

For the purposes of measurement, it is often necessary to tap sub-voltages from a primary voltage. This is done by means of voltage division. Illustrated below is a voltage divider consisting of two series-connected resistors R₁and R₂.

The supply voltage U to the outer terminals and this is then divided into the two sub-voltages U₁ and U₂. According to the voltage division law,

According to Ohm's law, the current in the voltage divider is

and the voltage drop across the two resistors is

If the expression for current as derived above is substituted into these two equations, the following equations are obtained for the two sub-voltages:

These equations apply only when no current is being tapped from the voltage divider, i.e. in the no-load state.

The interactive animation below shows a voltage divider whose supply voltage and resistance values can be adjusted with the mouse. If you modify these variables, you will be able to observe the corresponding effects on both sub-voltages.