Kirchhoff's laws (junction and loop rules)
Electric current and circuits · Physics
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Problem: A junction has three wires connected to it. Current I1 = 4A enters the junction. Current I2 = 15A leaves the junction. Find the current I3 in the third wire, assuming it enters the junction. Steps: 1. Apply Kirchhoff's Junction Rule: Sum of currents entering = Sum of currents leaving. 2. Let entering currents be positive and leaving be negative (or vice versa, as long as consistent). Entering: I1 + I3. Leaving: I2. 3. Equation: 4A + I3 = 15A. 4. Solve for I3: I3 = 15A - 4A = 11A. Answer: The current I3 is 11A flowing into the junction.