A circuit needs to be designed to measure the resistance R of a cylinder PQ to the best possible accuracy, using an ammeter A. a voltmeter V, a battery E and a current source Is (all assumed to be ideal). The value of R is known to be approximately 10 Ω, and the resistance W of each of the connecting wires is close to 10 Ω. If the current from the current source and voltage from the battery are known exactly, which of the following circuits provides the most accurate measurement of R?
a.
b.
c.
d.
1
(b)
2
(a)
3
(d)
4
(c)