College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 8

For the circuit shown in Figure P18.28, use Kirchhoff's rules to obtain equations for (a) the upper loop, (b) the lower loop, and (c) the node on the left side. In each case suppress units for clarity and simplify, combining like terms. (d) Solve the node equation for I 36. (e) Using the equation found in (d), eliminate I 36 from the equation found in part (b). (f) Solve the equations found in part (a) and part (e) simultaneously for the two unknowns for I 18 and I 12 , respectively. (g) Substitute the answers found in part (f) into the node equation found in part (d), solving for I 36. (h) What is the significance of the negative answer for I 12