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QPage 276: Q4: HC Verma: Concepts of Physics - Volume 2 Permanent Magnets Page 276: Q4 Solution: Let be the distance of a point on the axis of a bar magnet from …

⚠️ Common Exam Traps & Conceptual Pitfalls

Students often incorrectly apply the inverse square law ($1/r^2$) derived for electric charges or point masses to magnetic dipoles. Remember that a bar magnet is a dipole, and its axial field decays as $1/r^3$ at distances large compared to the magnet's length.

Let rr be the distance of a point on the axis of a bar magnet from its centre. The magnetic field at such a point is proportional to

Multiple Choice Options

  • A 1/r1/r
  • B 1/r21/r^2
  • C 1/r31/r^3
  • D none of these

Step-by-Step Verified Solution

**Answer:** (c) 1/r_. **Step-by-Step Explanation:** For a bar magnet (dipole), the field on the axis is proportional to 1/r_ at large distances.

All Questions in this Chapter

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