For the circuit shown in Figure P28.32, we wish
to find the currents I1, I2, and I3.Use Kirchhoff’s rules
to obtain equations for (a) the upper loop, (b) the lower
loop, and (c) the junction on the left side. In each case,
suppress units for clarity and simplify, combining the
terms. (d) Solve the junction equation for I3. (e) Using the
equation found in part (d), eliminate I3 from the equation
found in part (b). (f) Solve the equations found in parts
(a) and (e) simultaneously for the two unknowns I1 and I2.
(g) Substitute the answers found in part (f) into the junction
equation found in part (d), solving for I3. (h) What is
the significance of the negative answer for I2?