Current distribution in parallel circuits: Does the branch with the lowest resistance carry the greatest current when branches share the same voltage?
Correct Answer: True
Introduction / Context:Parallel circuits place components across the same two nodes, so each branch experiences the same voltage. This item checks the fundamental current-voltage-resistance relationship governing how current divides among parallel branches.
Given Data / Assumptions:
- Ideal voltage source maintains node-to-node voltage across all branches.
- Branches contain resistors (linear, time-invariant).
- Steady-state DC or AC using RMS values for magnitudes.
Concept / Approach:
Ohm’s law states I = V / R. In a parallel network, each branch current Ik equals V / Rk. If two branches share the same V, the smaller Rk produces a larger Ik. Thus, the branch with the lowest resistance draws the most current.
Step-by-Step Solution:
All branches have the same applied voltage V.For branch k: Ik = V / Rk.If Ri < Rj then Ii = V / Ri > V / Rj = Ij.Therefore, the lowest-resistance branch carries the maximum current.Verification / Alternative check:
Numerical example: V = 12 V; R1 = 3 Ω, R2 = 6 Ω. I1 = 4 A, I2 = 2 A. The lower resistance branch indeed carries twice the current.
Why Other Options Are Wrong:
- No need for other branches to be open; current division works with any number of branches.
- In AC, the same principle holds for resistive branches using RMS values.
- Power rating does not determine current; resistance and voltage do.
Common Pitfalls:
Confusing resistance with power rating or physical size. Also, treating parallel branches as if currents must be equal—this only occurs when the resistances are equal.
Final Answer:
True