(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

"Design a multirange voltmeter capable of full-scale deflection for 20.0V, 50.0V, and 100 V. Assume that the meter movement is a galvanometer that has a resistance of 60.0 ohms and gives a full-scale deflection for a current of 1.00 mA"

2. Relevant equations

V = IR

Kirchoff's Law's

3. The attempt at a solution

I know that the current through the galvanometer must be 1.00mA, meaning i'll need a large resistor in series with the galvanometer. I would be able to solve this no problem if only one voltage was needed, it is the variable voltages that throw me. So far, I believe i have a voltmeter (galv + large resistor) in parallel with a small resistor (so that most of the current flows through the small). I've attempted kirchoff's and equating v/r for each voltage, but there are too many variables for me to solve. Help? Thanks in advance

Example of a similar, simpler problem:

"A galvanometer requires a current of 1.5mA for full-scale deflection and has a resistance of 75 ohm, may be used to measure currents of much larger values. Calculate the value of the shunt resistor that enables the meter to be used to measure a current of 1 A and full-scale deflection"

Solution:

V = IR = (75)(1.5x10^-3) = (1-1.5x10^-3)R

R = .113 ohms

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# Homework Help: Design a multirange voltmeter

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