PhysicsHard116×since 2002Q7688A coil of n number of turns wound tightly in the form of a spiral with inner and outer radii r₁ and r₂ respectively. When a current of strength I is passed through the coil, the magnetic field at its centre will be :Aμ0nI2(r2−r1){{{\mu _0}nI} \over {2({r_2} - {r_1})}}2(r2−r1)μ0nIBμ0nIr2{{{\mu _0}nI} \over {{r_2}}}r2μ0nICμ0nIr2−r1loger1r2{{{\mu _0}nI} \over {{r_2} - {r_1}}}{\log _e}{{{r_1}} \over {{r_2}}}r2−r1μ0nIloger2r1Dμ0nI2(r2−r1)loger2r1{{{\mu _0}nI} \over {2({r_2} - {r_1})}}{\log _e}{{{r_2}} \over {{r_1}}}2(r2−r1)μ0nIloger1r2Check answerSkip