physics current electricity 問題

2010-04-19 9:11 pm

The figure shows a set-up of a potential divider. The internal resistance of all
cells and all ammeters are negligible.
http://xs.to/image-F3C5_4BCBE34D.jpg
a, Why is the calibration of ammeter A2 not neccessary in the process of
determining the e.m.f. of cell Y?
b, Can this method be used for determining the e.m.f. of cell Y if Y has an
internal resistance? Explain.

回答 (1)

天同

2010-04-19 9:56 pm

✔ 最佳答案

(a) There is no current flowing through ammeter A2 when the emf of cell Y equals to the potential difference across R1. This is why A2 needs not be well calibrated.

(b) Yes. As said above, because there is no current flowing through cell Y, there is no potential drop across its internal resistance. The terminal voltage thus equals to the emf of the cell.

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