- #1
moenste
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Homework Statement
The 4.0 V cell in the circuits shown below has zero internal resistance. An accurately calibrated voltmeter connected across YZ records 1.50 V. Calculate (a) the resistance of the voltmeter, (b) the voltmeter reading when it is connected across Y'Z'.
What do your results suggest concerning the use of voltmeters?
2. The attempt at a solution
(a) I = V / R = (4 - 1.5) / 60 = 0.0417 A
I = 1.5 / 40 = 0.0375 A
I that flows in the voltmeter = 0.0417 - 0.0375 = 0.00417 A
R = V / I = 1.5 / 0.00417 = 360 Ω
(b) No idea. I did try to some equations like 4 = 600 * I + I R2, but I think they lead into nothing. How can we find the voltmeter reading? It's a parallel circuit but now we don't know neither the V nor the current or the resistance.