Meters: A galvanometer with a resistance of 40.0 Ω deflects full scale at a current of 2.0 mA. What resistance should be used with this galvanometer in order to construct a voltmeter that can read a maximum of 50 V?
A) 25 kΩ
B) 27 kΩ
C) 29 kΩ
D) 31 kΩ
E) 35 kΩ

Question

Quizplus · Accepted Answer

To convert the galvanometer to a voltmeter that reads up to 50 V, use the formula R = (V/I) - Rg, where V is the maximum voltage (50 V), I is the full-scale deflection current (2.0 mA), and Rg is the galvanometer resistance (40 Ω). R = (50/0.002) - 40 = 25000 - 40 = 24960 Ω, which is approximately 25 kΩ.

Meters: a Galvanometer with a Resistance of 40