# I was studying avometer, and came across this paragraph which I find

1. Aug 18, 2009

### uzair_ha91

I was studying avometer, and came across this paragraph which I find confusing: "The voltage measuring part of the avometer is actually a multirange voltmeter. It consists of a number of resistances each of which can be connected in series with the moving coil galvanometer with the help of a switch called the range switch. The value of each resistance depends upon the range of the voltmeter which it controls...."
I thought that the resistances make up the range, so why does it say that their values depend upon the range? What range are we talking about here? Please clarify...

2. Aug 20, 2009

### Darryl

Re: Avometer

Im guessing, but I think they would be refering to the FSD for full scale deflection current of the moving coil galvanometer.

The series resistance will scale it's current based on I = V/R. V is the measured Voltage, and R is the total resistance of the moving coil galvanometer and the range resistance value.

This brings up the term "Ohms per volt" which is a measure of "goodness" of (mainly) analogue meters.
The AVO is a classic instrument rugged and accurage and a pleasure to use.