(a) A voltmeter and an ammeter can be connected as shown in Fig. 19-71a to measure a resistance R. If V is the voltmeter reading, and l is the ammeter reading, the value of R will not quite be V / l (as in Ohm€™s law) because some of the current actually goes through the voltmeter. Show that the actual of R is given by 1/R = 1/V €“ 1/RV, where RV is the voltmeter resistance. Note that R ≈ V / l if Rv >> R.
(b) A voltmeter and an ammeter can also be connected as shown in Fig. 19-71b to measure a resistance R. Show in this case that R = V / l €“ RA, where V and l are the voltmeter and ammeter readings and RA is the resistance of the ammeter. Note that R ≈ V / l if R A

ww ww (a) (b)