What is the formula to calculate total current in a series circuit?

• A. IT = IR1 + IR2 + IR3
• B. IT = VR1 + VR2 + VR3
• C. IT = 1/(1/R1 + 1/R2)
• D. IT = IR1 = IR2 = IR3

Answer: (D)

In a series circuit, the total current flowing through each component is the same due to the nature of the circuit configuration, which means that the total current (denoted as IT) is equal to the current through each individual resistor. Therefore, the expression IT = IR1 = IR2 = IR3 accurately represents this relationship, confirming that all resistors have the same current passing through them.

This principle arises from Kirchhoff's current law, which states that the current entering a junction must equal the current leaving the junction. In a series circuit, because there are no junctions between components, the same current flows sequentially through each resistor. Hence, the formula illustrates that the total current is consistent across all components in the series arrangement.

This consistency is critical when analyzing circuits, as it simplifies calculations related to voltage drops and total resistance.