A shunt is a

Very low resistance

{"type":"technical","methodBadge":"Concept & Principle","explanation":"A shunt is a very low-value resistance connected in parallel with a measuring instrument (typically a PMMC galvanometer) to extend its current-measuring range. By diverting a significant portion of the total current away from the meter movement, it prevents the instrument coil from being damaged by excessive current.","workingPrinciple":"According to the principle of current division, when a low resistance $R_{sh}$ is placed in parallel with a meter resistance $R_m$, the majority of the current $I$ flows through the path of least resistance. The shunt resistance is precisely calculated so that the meter only receives its full-scale deflection current $I_m$, while the remainder $I_{sh} = I - I_m$ flows through the shunt.","diagramSvg":"Shunt Connection CircuitMeter ($R_m$)Shunt ($R_{sh}$)$I$$I$","keyFormulas":["$R_{sh} = \\frac{R_m}{m - 1}$ — where $m = \\frac{I}{I_m}$ is the multiplying power of the shunt","$I_{sh} = I - I_m$ — Current division at the shunt junction"],"keyPoints":["Shunt resistance must always be in parallel with the moving coil instrument.","A lower $R_{sh}$ value results in a higher multiplying power ($m$) for the ammeter.","The shunt material is typically Manganin, chosen for its low temperature coefficient of resistance."],"advantages":["Allows measurement of very high currents using a standard low-range galvanometer.","Provides a protective bypass for the meter movement."],"disadvantages":["Increases heat dissipation if not sized correctly.","Accuracy depends on the thermal stability of the shunt material."],"applications":["Range extension of DC ammeters.","Current sensing in motor control drives and battery management systems."],"comparisonTable":[],"additionalInfo":["The resistance of the shunt is typically much smaller than the internal resistance of the meter ($R_{sh} \\ll R_m$).","Option A and D are incorrect because high resistance in parallel would not bypass enough current to protect the meter."],"answer":"C is correct — A shunt is a very low resistance connected in parallel to an ammeter to extend its current measuring range.","correctedOptions":["Very high resistance","Medium resistance","Very low resistance","High resistance"],"coreConcepts":["Current Division Rule","PMMC Instrument Modification","Multiplying Power of Shunt"],"crossTopicTip":"Remember that a 'shunt' always implies parallel connection, while a 'multiplier' (used for voltmeters) always implies series connection."}