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songoku
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Homework Statement
Two almost identical lead-acid accumulator batteries, X and Y, are connected with opposing polarities in a circuit which includes an ammeter, an ideal millivoltmeter and a resistor R as shown in figure below.
When S1 is closed with S2 left open, the millivoltmeter reads 50 mV. When S2 is closed with S1 remaining closed, the reading of the millivoltmeter changes by 20 mV and ammeter reads 5.0 A. What is the internal resistance of battery X ?
a. 4.0 x 10-3
b. 6.0 x 10-3
c. 10 x 10-3
d. 14 x 10-3
e. 16 x 10-3
Homework Equations
V = IR
The Attempt at a Solution
Should we consider internal resistance of Y, because it is said "two almost identical lead-acid accumulator batteries" ? ( I think because it is almost identical, Y also has internal resistance that should be considered ).
After S2 is closed, the reading changes by 20 mV --> I interpret this : the millivoltmeter reading becomes 30 mV.
Then I don't know...Thanks
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