ASVAB (Armed Services Vocational Aptitude Battery)Electronics Information (EI)Medium
A circuit contains three identical light bulbs connected in parallel to a 9V battery. If one of the bulbs has a resistance of 3 ohms, what is the total current drawn from the battery?
- A9 A
- B1 A
- C27 A
- D3 A
Show answer & explanationAnswer & explanation
Correct answer: A. 9 A
In a parallel circuit, the voltage across each branch is the same as the source voltage. For each bulb, I = V/R = 9V / 3Ω = 3A. Since there are three identical bulbs in parallel, the total current is the sum of the currents through each bulb: 3A + 3A + 3A = 9A.
Why the other options are wrong
- B. This would be the current for only one bulb or if the bulbs were in series with higher total resistance.
- C. This would be the total resistance divided by the voltage, which is incorrect for parallel current calculation.
- D. This is the current through a single bulb, not the total current.
Parallel Circuit Current
In a parallel circuit, the total current drawn from the source is the sum of the currents flowing through each individual branch.
- Voltage is the same across all parallel components.
- Current divides among parallel branches.
- Total current is the sum of individual branch currents (Kirchhoff's Current Law).
Memory trick: Currents Combine in Parallel Paths.