Chapter 27, Problem 51P

In Fig. 27-58, a voltmeter of resistance R_v= 300 Ω and an Ammeter of resistance R_A = 3.00 Ω are being used to measure a resistance R in a circuit that also contains a resistance R₀ = 100 Ω and an ideal battery with an emf of ℰ = 12.0 V. Resistance R is given by R = Vli, where V the potential across R and i is the ammeter reading. The voltmeter reading is V’, which is V plus the potential difference across the ammeter. Thus, the ratio of the two meter readings is not R but only an apparent resistance R’ = V'li. If R = 85.0 Ω, what arc (a) the ammeter reading, (b) the voltmeter reading, and (c) R’?(d) If R_A is decreased, does the difference between R' and R increase, decrease, or remain the same?

Figure 27-58 Problem 51.