Two resistors, 8 Ω and 4 Ω, are in parallel across a 12 V source. What is the total current drawn from the source?

Two resistors, 8 Ω and 4 Ω, are in parallel across a 12 V source. What is the total current drawn from the source?

• A. 2.0 A
• B. 4.5 A
• C. 6.0 A
• D. 3.0 A

Answer: (B)

When resistors are in parallel, they share the same voltage from the source, and the total current is the sum of the currents in each branch. For this circuit, the 8 Ω branch draws I1 = 12 V / 8 Ω = 1.5 A, and the 4 Ω branch draws I2 = 12 V / 4 Ω = 3 A. Adding them gives a total current of 1.5 A + 3 A = 4.5 A. Another way to see it is to find the equivalent resistance: 1/R_eq = 1/8 + 1/4 = 3/8, so R_eq = 8/3 Ω. Then I = V / R_eq = 12 V / (8/3 Ω) = 4.5 A.

When resistors are in parallel, they share the same voltage from the source, and the total current is the sum of the currents in each branch. For this circuit, the 8 Ω branch draws I1 = 12 V / 8 Ω = 1.5 A, and the 4 Ω branch draws I2 = 12 V / 4 Ω = 3 A. Adding them gives a total current of 1.5 A + 3 A = 4.5 A. Another way to see it is to find the equivalent resistance: 1/R_eq = 1/8 + 1/4 = 3/8, so R_eq = 8/3 Ω. Then I = V / R_eq = 12 V / (8/3 Ω) = 4.5 A.