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QPage 248: Q11: HC Verma: Concepts of Physics - Volume 2 Magnetic Field Due to a Current Page 248: Q11 Solution: Quite often, connecting wires carrying currents in opposite…

⚠️ Common Exam Traps & Conceptual Pitfalls

Students frequently assume that opposite currents make their magnetic fields cancel at every point, but magnetic fields add vectorially; only the net external field averages to zero when the wires are tightly twisted, while locally the fields may reinforce or oppose depending on position.

Quite often, connecting wires carrying currents in opposite directions are twisted together in using electrical appliances. Explain how it avoids unwanted magnetic fields.

Step-by-Step Verified Solution

**Answer:** Twisting the wires cancels the magnetic fields produced by the currents in opposite directions. **Step-by-Step Explanation:** For two parallel wires carrying opposite currents, the fields between them reinforce and the fields outside cancel. By twisting the wires, the fields from consecutive twists are in opposite directions and average to zero over a long length, minimising unwanted magnetic fields.

All Questions in this Chapter

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