- #1

kaspis245

- 189

- 1

## Homework Statement

A circuit contains 9V battery ,which internal resistance is unknown, an ammeter and a voltmeter, whose resistances are also unknown. When a resistor was connected to the voltmeter in parallel, the voltmeter's value was reduced 2 times and the ammeter's value doubled. What did the voltmeter show before the resistor was connected?

## Homework Equations

Kirchhoff's Rules

## The Attempt at a Solution

Here's my drawing:

I know that:

##I_2=2I_1##

##V_1=2V_2##

From first drawing I get:

##V_1=I(r_1+r)##

##I_1=I-9/r##

If I could express the same values (V

_{1}and I

_{1}) maybe I could equate them and get the answer, but I am not sure how to do this.