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A magnetic needle of negligible breadth and thickness compared to its length, oscillates in a horizontal plane with a period T . The period of oscillation of each part obtained on breaking the magnet into n equal parts and perpendicular to the length is

Options

  1. AT
  2. BT n
  3. Cn T
  4. D1 n

Correct answer

B. T n

Step-by-step solution

T = 2 π I M B on breaking n equal parts perpendicular to length I ′ = 1 12 m n l n 2 of each part I ′ = I n 3 , M ′ = M n T ′ T = I ′ M ′ × M I = 1 n 3 × n = 1 n ⇒ T ′ = T n

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