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SarkariResultOutBMS · 2024

Previous Year Question

Two thin parallel wires carry currents along the same direction. The force experienced by one due to the other is
  1. Zero
  2. Perpendicular to the lines and repulsive
  3. Parallel to the lines
  4. Perpendicular to the lines and attractive

Correct answer: D

Explanation

Two long parallel conductors carrying current in the same direction attract each other. Each wire lies in the magnetic field created by the other and experiences force F=I l×B toward the neighboring wire. Hence option D is correct.

Formula

F/L=μI1I2/(2πd); same-direction currents attract

Step-by-step solution

Parallel Conductors explanatory diagram

Correct Answer

D — Perpendicular to the lines and attractive

Concept and Reasoning

Two long parallel conductors carrying current in the same direction attract each other. Each wire lies in the magnetic field created by the other and experiences force F=I l×B toward the neighboring wire. Hence option D is correct.

Calculation / Key Relation

F/L=μI1I2/(2πd)

same-direction currents attract

Exam Takeaway

Same direction → attraction; opposite direction → repulsion.

Common Mistake

Do not apply the electrostatic “like repels” rule to parallel current-carrying conductors.

Common mistake

Do not apply the electrostatic “like repels” rule to parallel current-carrying conductors.

Exam tip

Same direction → attraction; opposite direction → repulsion.

Quick method

Same direction → attraction; opposite direction → repulsion.