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## Homework Statement

For the values shown in the figure below, calculate (a) the current through the ammeter A

_{1}, (b) the current through the ammeter A

_{2}, (c) the PD across R

_{2}.

Assume that the internal resistance of each cell and the resistance of each ammeter is negligible.

Answers: (a) 0.05 A, (b) 0.0125 A, (c) 0.5 V

**2. The attempt at a solution**

(c) V = IR = 0.05 * 10 = 0.5 V

(a-b) We use Kirchhoff's rules: current flowing from E

_{1}is I

_{1}, current entering R

_{1}is I

_{1}- I

_{3}and current entering E

_{2}is I

_{3}.

So we get 2 = 40 (I

_{1}- I

_{3}) + 10 (

_{1}- I

_{3})

1.5 = - 40 (I

_{1}- I

_{3}), minus since current is moving from left to right while we are moving in an anti-clockwise direction.

2 = 50

_{1}- 50 I

_{3}

1.5 = -40 I

_{1}+ 40 I

_{3}(multiply by 1.25 and sum up)

3.875 = 0 which is uncorrect.

What am I doing wrong?