What are Shunt Resistors?

What are Shunt Resistors?

A shunt is an electrical device that generates a low resistance path for current.  This allows the current to flow to another point in the circuit.  A shunt may also be called an ammeter shunt or a current shunt resistor.  
 
Shunt resistors are typically used to measure high currents with low levels of associated resistance.  Shunting is literally translated as shifting or following a force along a set path.  
 
In many cases, the current needs to be measured.  Common applications include overcurrent protection, 4-20mA systems, battery charging, and H-bridge motor control.  Using ohm's law equations, voltage and current levels can be measured in amperes.  This requires the resistor to be connected in parallel with the ammeter.  The resulting current division makes it possible to measure the ampere level.