Two unlike magnetic poles of strength 10 A-m each are held in air at a distance of O- IO m from each other. What is the magnetic force of attraction between them ?
Answer: (D) 1 × 10⁻³ N.
The force of attraction between the unlike magnetic poles is
1×10⁻³ N. This is calculated using the formula involving permeability of free space, magnetic pole strengths and distance.
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The magnetic force F between two magnetic poles is given by:
F = μ0 ⋅m1 ⋅m2/4πr²
Here,
μ0 = 4π × 10⁻⁷ N/A² ,m = m = 10A\cdotpm,
r = 0.1m.
Substituting the values:
F = 4π × 10⁻⁷ . 10 . 10/4π. (0.1)² = 10⁻⁵/0.01 = 1 × 10⁻³N
Answer: (D) 1 × 10⁻³ N
So, the magnetic force of attraction is
1 × 10⁻³ N.