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a) $8\textrm{V}$
b) $16 \textrm{V}$
c) $8 \textrm{V}$
d) $-5.76 \mu\textrm{C}$

Giancoli 6th Edition, Chapter 19, Problem 52


Chapter 19, Problem 52 is solved.

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Clarificaiton Please

I am not sure as to why the 4.4 resistor is used in part "a." How can i know which one to choose? I would have thought it is the 8.8 resistor since current travels from positive to negative potential.

Thanks for the question tysonclay.

Part (a) asks "What is the potential at point "a"..."

When a question is worded like this, where it asks for the "potential", what it's really asking for is the "potential difference". It's never possible to measure an absolute potential. Only potential differences are ever measurable. In the context of a circuit with a battery, the word "potential" really means the "potential difference with respect to the negative terminal". For the electrical outlet in a house, 120 Volts is the potential difference between one prong with respect to the other prong of the plug, for example.

So, Part (a) could be reworded "What is the potential difference between point "a" with respect to the negative terminal of the battery?" This is what Ohm's Law tells us, using the 4.4 Ohm resistor.

If the resistors are in series, why does Voltage a and Voltage b equal each other? I thought it was just the current that's uniform throughout resistors in series.