To use miliammeter as voltmeter series resistance: where,

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To use miliammeter as voltmeter series resistance:
where,
V = Required voltage
I_m = Full scale reading
R_m = Meter resistance
n = Multiplying factor of meter

1. R_s = R_m (n – 1)
2. R_s = V/I_m = R_m
3. R_s = V/I_m + R_m
4. None of these

Correct Option: B

To use milliammeter as voltmeter series resistance.

R_s =	V	- R_m
	I_m

or

R_s =		V	- 1		= R_m(n-1)
		I_mR_m

where,
n = V/V_m
= Voltage to be measured/Voltage of the meter
where,
V = Required voltage
I_m = Full scale reading
R_m = Meter resistance