Question 56

The Correct Answer is B **Explanation of Option B (Correct):** To minimize magnetic field interaction (crosstalk or interference) between electrical conductors carrying current, two main strategies concerning their physical arrangement are employed: orientation and distance. 1. **Orientation (at right angles):** Magnetic fields produced by a current-carrying wire circulate around the conductor. If a second conductor is placed parallel to the first, the magnetic flux from the first conductor will link efficiently with the second, inducing a voltage (mutual inductance). If the conductors are placed **at right angles (perpendicular)** to each other, the mutual inductance approaches zero because the magnetic field lines from one conductor barely link, or link orthogonally, with the current path of the other conductor. This significantly reduces interaction. 2. **Distance (as far as practicable from each other):** The strength of a magnetic field diminishes rapidly with distance (typically following an inverse square law or $1/r$ relationship for a long wire). By placing the conductors **as far as practicable from each other**, the magnetic field intensity incident upon the second conductor is minimized, further reducing the induced interaction. Therefore, the combination of minimizing mutual inductance via perpendicular orientation and minimizing field strength via maximum separation makes "at right angles and as far as practicable from each other" the best practice. **Explanation of Incorrect Options:** * **A) at right angles and as close as possible to each other:** While the right-angle orientation minimizes mutual inductance, placing the conductors as close as possible maximizes the field strength (B-field) experienced by the second conductor, counteracting the benefit of the orientation. * **C) parallel to and as far as practicable from each other:** Although maximizing distance reduces the field strength, placing conductors **parallel** maximizes mutual inductance (flux linkage). Parallel arrangements are the worst for minimizing interaction, even when separated. * **D) parallel and as close as possible to each other:** This configuration is the absolute worst practice for minimizing magnetic interaction. Parallel placement maximizes mutual inductance (flux linkage), and minimum distance maximizes the magnetic field strength acting on the neighboring conductor.