To determine the resistance ( R ) of a wire, a circuit is designed below, The V-I characteristic curve for this circuit is plotted for the voltmeter and the ammeter readings as shown in figure. The value of R is ______ Ω.
Answer: 2500
Solution
The circuit is a voltmeter (resistance 10 kΩ) placed across the series combination of R and the ammeter; the equivalent resistance seen by the source is
Req=104+R104R
From the graph, at E=4 V, I=2 mA, so Req=E/I=2000Ω.