when a volt meter's range is extended the series resistor is used to dropout the maximum amount of voltage. it is a precision resistor having High resistance.Multiplier resistor are high resistance connected in Series with Permanent magnet moving coil Meter(PMMC) meter whose rating is to be extended.these Multipliers are used with DC and AC both meters and Analog/digital meters.

Multiplier resistancae is always connected in series with meter. The purpose of this resistor is to drop the voltage so that excessive voltage will not damage the meter. Noramallly a meter has full scale voltage in mV and to extend the range this method is adopted.

Formula is based on ohms law where to calculate the resistance is based on voltage divided by current. In this formula we have two voltages one is full scale voltage of meter and another is required voltage which is always higher than fulll scale voltage of meter.

- Rm is internal resistance of Meter(Permanent magnet moving coil Meter(PMMC)/Galvanometer)
- Im is the full scale current of Meter(Permanent magnet moving coil Meter(PMMC)/Galvanometer)
- Vreq is the required voltage at which meter range is extended.

Insert the value of Im,Rm & Vreq :