Goodmarks
Sign in

Physics · Magnetic field due to a magnetic dipole (bar magnet) along its axis and perpendicular to its axis, torque on a magnetic dipole in a uniform magnetic field

A magnet makes 40 oscillations per minute at a place having magnetic field inten

A magnet makes 40 oscillations per minute at a place having magnetic field intensity of \( 0.1 \times 10^{-5} \) T. At another place, it takes 2.5 seconds to complete one vibration. The value of earth's horizontal field at that place is

  • A. \( 0.25 \times 10^{-6} \mathrm{T} \)
  • B. 0.36 \( \times 10^{-6} \) т
  • C. \( 0.66 \times 10^{-8} \mathrm{T} \)
  • D. 1.2 \( \times 10^{-6} \) न

Step-by-step solution

For the same magnet, the time period T is inversely proportional to the square root of the magnetic field: T ∝ 1/√B. At first place, T1 = 60/40 = 1.5 s, B1 = 0.1×10^{-5} T = 1×10^{-6} T. At second place, T2 = 2.5 s. Using T1/T2 = √(B2/B1), we get B2 = B1 (T1/T2)^2 = (1×10^{-6})×(1.5/2.5)^2 = 0.36×10^{-6} T.
Practise more in this unitView MCQsSign up for full question bank

Related MCQs