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A square coil of edge I having n turns carries a current i . It is kept on a smooth horizontal plate. A uniform magnetic field B exists in a direction parallel to an edge. The total mass of the coil is m . The minimum value of B for which the coil will start tipping over

Options

  1. Am g n i l 2
  2. B2 m g n i l
  3. Cm g 2 n i l
  4. Dm g n i l '

Correct answer

C. m g 2 n i l

Step-by-step solution

Deflecting torque = n i​ A B s i n 90 = n i l 2 B Restoring torque = m g l 2 For tipping n i l 2 B ≥ m g l 2 ⇒ B ≥ m g 2 n i l ∴ B m i n = m g 2 n i l

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