Question bank/NEET UG/Physics

NEET UGPhysicsModerateRe-NEET 2026

Consider a long solenoid of length ll and radius rr. If nn is the number of turns per unit length and μ0\mu_0 is the permeability of free space, the inductance of the solenoid is :

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Sol. Self inductance of solenoid
L=NϕiL = \frac{N\phi}{i}
L=NBAiL = \frac{NBA}{i}
L=Nμ0niAi[n=Nl]L = \frac{N\mu_0niA}{i} \left[ n = \frac{N}{l} \right]
L=Nμ0nAL = N\mu_0nA
L=(Nl)μ0nAlL = \left( \frac{N}{l} \right) \mu_0nAl
L=μ0n2AlL = \mu_0n^2Al
L=μ0n2πr2l  [∵A=πr2]L = \mu_0n^2\pi r^2l \; [\because A = \pi r^2]

Source: geekyrakshit/indian-exam-questions / reneet2026-code50

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