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NEET2026PhysicsChapterActual

A uniform straight magnetized wire has a magnetic moment M . If it is bent into an arc of a circle such that it subtends an angle of 90^ at the centre of the circle, what will be the new magnetic moment of the wire?

Options

  1. AM 2
  2. B2 M
  3. C2M
  4. D2 2 M

Correct answer

D. 2 2 M

Step-by-step solution

Let the pole strength of the magnetized wire be m and its length be L . The initial magnetic moment is given by: M = m L When the wire is bent into an arc of a circle of radius R subtending an angle = 90^ = 2 radians at the centre, the length of the arc remains L . L = R = R ( 2 ) R = 2L The new magnetic moment M' depends on the shortest distance (chord length) d between the two poles. From the geometry of the circle, the chord length for an angle of 90^ is: d = R^2 + R^2 = 2 R Substituting the value of R : d = 2 (

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