For the values shown in the figure below, calculate (a) the current through the ammeter A1, (b) the current through the ammeter A2, (c) the PD across R2.
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 E1 is I1, current entering R1 is I1 - I3 and current entering E2 is I3.
So we get 2 = 40 (I1 - I3) + 10 (1 - I3)
1.5 = - 40 (I1 - I3), minus since current is moving from left to right while we are moving in an anti-clockwise direction.
2 = 50 1 - 50 I3
1.5 = -40 I1 + 40 I3 (multiply by 1.25 and sum up)
3.875 = 0 which is uncorrect.
What am I doing wrong?