A current-carrying solenoid is filled with magnesium having magnetic susceptibility χ = 1.2×10⁻⁵. The percentage increase in the magnetic field is:
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Question

A current-carrying solenoid is filled with magnesium having magnetic susceptibility χ = 1.2×10⁻⁵. The percentage increase in the magnetic field is:

G1 Physics · Accepted Answer

For a linear magnetic material, μr = 1+χ. The magnetic field in the solenoid changes from B₀ = μ₀nI to B = μ₀μr nI. Therefore the fractional increase is (B-B₀)/B₀ = μr-1 = χ. Percentage increase: χ×100 = 1.2×10⁻⁵×100 = 1.2×10⁻³ % = (6/5)×10⁻³ %. Correct option: A.