FAA Aviation Mechanic General (AMG)Fundamentals of Electricity and ElectronicsMedium
At a junction in a DC parallel circuit, two branch currents of 4 amps and 6 amps flow into the junction. According to Kirchhoff's Current Law, what must be the current flowing out of the junction through the third branch?
- A2 amps
- B10 amps
- C4 amps
- D6 amps
Show answer & explanationAnswer & explanation
Correct answer: B. 10 amps
Kirchhoff's Current Law states that the total current entering a junction must equal the total current leaving it. Since 4A + 6A = 10A enters, 10A must leave through the remaining branch.
Why the other options are wrong
- A. This would only be correct if currents were subtracted, which is not how KCL works at a junction.
- C. This ignores the second incoming current entirely.
- D. This ignores the first incoming current entirely.
Kirchhoff's Current Law (KCL)
The algebraic sum of currents entering a junction equals the sum of currents leaving it, based on conservation of electric charge.
- Also called the junction rule
- Total current in = total current out
- Fundamental to analyzing parallel and combined circuits
Memory trick: 'What flows in must flow out' - no charge is lost at a junction.