Kirchhoff's Circuit Laws: Example 1

Question:

The small DC circuit shown below has failed in service owing to excessive currents. A review of the circuit voltages and currents needs to be made to aid the inspection process. For this purpose, determine the currents and voltages in the circuit shown below. Apply Kirchhoff’s laws to your circuit to confirm the accuracy of the currents and voltages present within the circuit.

Answer:

Step 1: Convert R2 and R3 from parallel to series.

Step 2: Convert R4, R5 & R6 from parallel to series.

Step 3: Combine R1, R7 and R8 as they are in series.

Step 4: Calculate the total circuit current.

Step 5: Calculate voltage drops through sections of circuit. Remember voltages are equal through parallel branches of circuits, therefore we can analyse the voltage drops as a series circuit seen below.

Step 6: Calculate currents going through each resistor.