Finding a Resistance With a The Potential Divider
The potential divider is a device designed to limit the voltage across a pair of terminals for whatever reason. It does this by placing a resistor
between the output terminals, in series with another resistor
as shown in the diagram below.
The input voltage
is split in the ratio of the two resistances, so that the output voltage is given by
Eitherorcan be replaced by a variable voltage so that
can be varied with a dial. Ifis replaced with a variable resistor of maximum resistance
thencan vary between
and
where for the latter, the variable resistance is set to zero.
If R-2 is replaced with a variable resistor of maximum resistancethencan vary between 0 and
and
A potential divider can act as a safety device, because if there is a short circuit in the input circuit then thewill limit the current and if there is a short circuit in the output circuit thenwill limit the resistance.
A potential divider can be used to measure a resistance
Connect in in position ofand measurethen
Ifandare known then
can be calculated.