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Question: Answered & Verified by Expert
A circular coil carrying current I has radius R and magnetic field at the centre is B. The distance from the centre along the axis of the same coil where the magnetic field will be B8 is
PhysicsMagnetic Effects of CurrentJEE Main
Options:
  • A R2
  • B R3
  • C 2R
  • D 3R
Solution:
1887 Upvotes Verified Answer
The correct answer is: R3
Bcenter=μ0nI2R=B

Bx=B8=μ0nIR22(R2+x2)3/2

18μ0nI2R=μ0nIR22(R2+x2)3/2

18R3=1(R2+x2)3/2

12R=1(R2+x2)12

4R2=R2+x2

x2=3R2

x= 3  R

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