Question

Two similar magnets, each of length 5 cm weighing 50 g-wt made from the magnico alloy developed by the Soviet scientists Zaimovskii and L'vov, are placed freely in a vertical glass tube with like poles facing each other (Fig.). The upper magnet is suspended in air over the lower magnet so that the distance a between the neighbouring poles of the magnets is 3 mm. Find the strength of the poles of these magnets. Will the distant poles affect the distance between the magnets?

  

Answer 1

Answer: m = 66 e. m. u.

Explanation:

The force of interaction between the neighbouring like poles is F₁ = m²/a²; since a < l, the force of interaction between the like poles is approximately F₂ = m³/4l², and the force of interaction between the unlike poles F₃ = m²/l²;

The forces F₂ and F₃ are negligibly small in comparison with F₁, and therefore the field strengths can be determined with sufficient accuracy from force F₁ . Setting F₁ = P, we have