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

The distance between two magnetic poles is doubled and their pole-strength is al

The distance between two magnetic poles is doubled and their pole-strength is also doubled. The force between them

  • A. Increases to four times
  • B. Decreases by half
  • C. Remains unchanged
  • D. Increases to two times

Step-by-step solution

According to Coulomb's law for magnetic poles, the force is proportional to the product of pole strengths divided by the square of the distance. Doubling both pole strengths multiplies the numerator by 4, but doubling the distance multiplies the denominator by 4, so the ratio remains the same. Hence the force is unchanged.
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