Circuit Theorems and Conversions — Engineering Board Exam Practice Questions

26 free engineering board exam reviewer questions on Circuit Theorems and Conversions (DC Circuits), each with the correct answer and a worked solution.

  1. Three 30, resistors are connected as a delta (triangle). What is the resistance between any two corners?
  2. Three branches are connected in parallel as shown, with V1=6 V, V2=6 V, V3=30 V, R1=12, , R2=12, , and R3=12, . Use Millman's theorem to…
  3. The bridge network shown has R1=30, , R2=60, , R3=15, , R4=30, , and R5=90, and is driven by a 36 V source. Use a delta-wye conversion to…
  4. In the circuit shown, V1=12 V, V2=6 V, R1=15, , R2=2, , and R3=10, . Use superposition to find the net current through R2 (magnitude).
  5. For the circuit shown, V=20 V, R1=6, , R2=2, , and R3=12, . Find the Thevenin resistance RTh at terminals a-b.
  6. In the circuit shown, V=48 V, R1=10, , R2=2, , and RL=5, . Use Thevenin's theorem to find the power dissipated by RL.
  7. A circuit has a Thevenin equivalent of 20 V and 8, . What is the maximum power it can deliver to a load?
  8. A circuit has a Thevenin equivalent of VTh=10 V and RTh=5, . What current flows when a 15, load is connected?
  9. When using superposition to find the effect of one source, the other independent voltage sources and current sources are replaced by
  10. Three branches are connected in parallel as shown, with V1=9 V, V2=18 V, V3=12 V, R1=12, , R2=3, , and R3=6, . Use Millman's theorem to…
  11. The Y (wye) network shown has RA=10, , RB=30, , and RC=15, . Find the equivalent delta resistor RAB connected between terminals A and B.
  12. The delta network shown has RAB=30, , RAC=90, , and RBC=60, . Find the equivalent Y resistor RB connected to terminal B.
  13. The delta network shown has RAB=120, , RAC=60, , and RBC=180, . Find the equivalent Y resistor RA connected to terminal A.
  14. A source V=24 V with internal resistance Rs=15, supplies a variable load RL, as shown. Find the power delivered to the load when RL=30…
  15. A source V=48 V with internal resistance Rs=15, supplies a variable load RL, as shown. Find the maximum power that can be delivered to the…
  16. In the circuit shown, V1=24 V, V2=6 V, R1=15, , R2=10, , and R3=3, . Use superposition to find the current through R2 (taken positive…
  17. In the circuit shown, V1=15 V, V2=30 V, R1=15, , R2=10, , and R3=6, . Use superposition to find the current through R2 (taken positive…
  18. For the circuit shown, I=6 A, R1=2, , and R2=4, . Find the Norton resistance RN seen at terminals a-b.
  19. For the circuit shown, I=10 A, R1=5, , and R2=15, . Find the Norton current IN at terminals a-b.
  20. For the circuit shown, V=24 V, R1=4, , R2=12, , and R3=8, . Find the Thevenin voltage VTh at terminals a-b.
  21. In the circuit shown, V=30 V, R1=10, , R2=5, , and RL=5, . Use Thevenin's theorem to find the current through RL.
  22. For the circuit shown, V=9 V, R1=15, , and R2=10, . Find the Thevenin resistance RTh seen looking into terminals a-b.
  23. For the circuit shown, V=36 V, R1=8, , and R2=4, . Find the Thevenin voltage VTh seen at terminals a-b.
  24. A source V=36 V with internal resistance Rs=6, supplies a variable load RL, as shown. For what value of RL is the power delivered to the…
  25. Convert the current source and parallel resistor shown (I=5 A, R=8, ) into an equivalent voltage source in series with a resistor. Find…
  26. Convert the voltage source and series resistor shown (V=20 V, R=5, ) into an equivalent current source in parallel with a resistor. Find…