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⚛️ Physics  ·  Magnetism and Matter  ·  NEET & JEE

A magnetic needle free to rotate in a vertical plane oriented along the magnetic meridian dips at an angle of 60° at a place where the horizontal component of Earth's field is 0.3 × 10⁻⁴ T. The vertical component of Earth's magnetic field at that place is approximately:

Answer: 0.52 × 10⁻⁴ T.

  • A 0.30 × 10⁻⁴ T
  • B 0.17 × 10⁻⁴ T
  • C 0.52 × 10⁻⁴ T
  • D 0.60 × 10⁻⁴ T

Correct answer: C. 0.52 × 10⁻⁴ T

Explanation: tan(dip) = Bv/Bh, so Bv = Bh tan(60°) = 0.3 × 10⁻⁴ × 1.732 ≈ 0.52 × 10⁻⁴ T.

Bar Magnet Field LinesNSfield lines: N → S (outside magnet)

Magnetic field lines form closed loops: outside the bar magnet they run from the N pole to the S pole; inside, they continue from S back to N, so the lines never start or end anywhere.

Concept context

Bar magnets, Earth's magnetism, and how different materials respond to an external magnetic field - diamagnetic, paramagnetic, and ferromagnetic behaviour.

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