What type of ohmmeter is used to measure low values of resistance?

• A. Megohmmeter
• B. Bridge
• C. Shunt
• D. Micro-ohmmeter

Answer: (C)

When you need to measure very small resistances, you use a micro-ohmmeter. These instruments are built to resolve tiny voltage drops with a known, small test current, often using four-wire (Kelvin) sensing so that the resistance of the leads and contacts doesn’t skew the result. That combination—accurate low-current excitation plus precise voltage measurement and separate sense lines—lets you read resistances in the micro-ohm range, which is exactly what you need for things like contact resistance, wire bundles, or tiny components.

Megohmmeters, on the other hand, are for insulation resistance in the mega-ohm range, not for tiny values. A bridge can measure unknown resistances by balancing against known standards, but it isn’t optimized for measuring very low resistances with the level of precision micro-ohmmeters provide. A shunt is a low-value resistor used to convert current to a voltage for ammeters, not an instrument for measuring the resistance of a component directly.