Problem 4.54 A 4 kOhm resistor is placed in parallel with the current source in the circuit. Assume you have been asked to
calculate the power developed by the current source.
Part A: Which method of circuit analysis would you recommend? Solution: Nodal Analysis requires 3 node equations Mesh Analysis requires 4 mesh equations Nodal Analysis is easier Note, Mastering Engineering seems to think mesh analysis is easier; either answer was accepted here. Part B: Find the power developed in the current source if i = 20mA Express your answer with appropriate units. The voltage at the top of the circuit = Va. The node voltage connecting the 2.5 kOhm, 1k Ohm, and 5k Ohm resistors is Vb. The node voltage connecting the 2 kOhm, 1kOhm, and 1kOhm resistors is Vc. The remaining node voltage = 0 Solution: Using Nodal Analysis i = 20 mA = (Va – Vb)/2500 + (Va – Vc)/2000 + Va/4000 (Va – Vb)/2500 = Vb/5000 + (Vb – Vc)/1000 (Vb – Vc)/1000 + (Va – Vc)/2000 = Vc/1000 Solving Va = 26.7V Vb = 13.3V Vc = 10.7V The current developed in the source is then 20mA * 26.7V = 0.53 W