Voltage divider
Online calculator for calculating the values on an unloaded voltage divider
On this page you can calculate the voltages and resistances of a voltage divider. To calculate it, two voltages and one resistance or two resistances and one voltage must be known.
To calculate, enter three values in one of the following combinations:
- 2 voltage values and 1 resistance value
- 1 voltage value and 2 resistance values
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Voltage divider formulas
The voltage divider is a series circuit of resistors that divide an electrical voltage. The ratio of the partial voltages corresponds to the ratio of the resistances. So for the calculation of the partial voltage \(\displaystyle U_2\) at \(\displaystyle R_2\) can be calculated:
\(\displaystyle U_2=\frac{U_{ges}} {R_{ges}} · R_2\)
Alternatively, the partial voltage \(\displaystyle U_2\) at \(\displaystyle R_2\) can be calculated using the current \(\displaystyle I\). To do this, the total resistance is first calculated as follows:
\(\displaystyle R_{ges}=R_1+R_2 \)
Assuming the total voltage is known, the current \(\displaystyle I \) can be determined according to Ohm's law:
\(\displaystyle I=\frac{U_{ges}} {R_{ges}}\)
The partial voltage at \(\displaystyle \small R_2\) can be calculated:
\(\displaystyle U_2=R_2 · I\)
Resistor \(\displaystyle \small R_1\)
\(\displaystyle R_1=\frac{U_1 · R_2}{U_2}\,=\,\frac{U_1 · R_2}{U_G-U_1}\)
Resistor \(\displaystyle \small R_2\)
\(\displaystyle R_2=\frac{U_2 · R_1}{U_1}\,=\,\frac{R_1 (U_G-U_1)}{U_1}\)
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