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NDA 1 2025 GAT, question 142

Topic: Physics

Q142

A current through a horizontal power line flows in east to west direction. What will be the direction of magnetic field at a point directly below it when viewed from east end ?

  1. (a) Clockwise in a plane perpendicular to the wireCorrect answer
  2. (b) Anti-clockwise in a plane perpendicular to the wire
  3. (c) Clockwise in a plane of parallel to the wire
  4. (d) Anti-clockwise in a plane of parallel to the wire

Solution.

Answer: (a) Clockwise in a plane perpendicular to the wire

  1. Viewed from the east end, the current flows away from the observer, toward the west.
  2. Point the right thumb away from the eye: the curled fingers run clockwise.
  3. The magnetic field circles the wire in a plane perpendicular to it.