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Two long coaxial solenoids are wound with thin insulated wire on a tube of cross-sectional area A = 10 cm² and length 20 cm. If one solenoid has 300 turns and the other has 400 turns, what is their mutual inductance? (Take μ0 = 4π × 10⁻⁷ T m A⁻¹)
- 2.4π × 10⁻⁵ H
- 4.8π × 10⁻⁴ H
- 4.8π × 10⁻⁵ H
- 2.4π × 10⁻⁴ H
Correct answer: 2.4π × 10⁻⁴ H
Solution
M = mu0*N1*N2*A/l = 4*pi*1e-7*300*400*(10e-4)/0.2 = 2.4*pi*1e-4 H.
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