In a parallel circuit with a 24 V source and three resistors in parallel: R1 = 8 Ω, R2 = 12 Ω, R3 = 4 Ω. What is the total current drawn from the source?

• A. 9 A
• B. 11 A
• C. 13 A
• D. 15 A

Answer: (B)

In a parallel circuit, the voltage across every branch is the same as the source, so the total current is the sum of the currents in each branch. Calculate each branch current with I = V/R: the current through the 8 Ω resistor is 24/8 = 3 A, through the 12 Ω resistor is 24/12 = 2 A, and through the 4 Ω resistor is 24/4 = 6 A. Adding them gives a total current drawn from the source of 3 + 2 + 6 = 11 A. A quick check using equivalent resistance (1/Req = 1/8 + 1/12 + 1/4) yields Req ≈ 2.18 Ω, and 24 V divided by that gives about 11 A as well. The total current is 11 A.