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QNEET-2016-Ph-1062: NEET 2016 Physics - Class 12 NEET-2016-Ph-1062 Solution: A long straight wire of radius a carries a steady current I.…
A long straight wire of radius a carries a steady current I. The current is uniformly distributed over its cross-section. The ratio of the magnetic fields B and B' at radial distance a/2 and 2a respectively from the axis of the wire is 1 4 1/4 1/2
Multiple Choice Options
- A 1
- B 4
- C 4 1 _
- D 2 1 _
Step-by-Step Verified Solution
For points inside the wire i.e., (r � R)
Magnetic field B = _ 0 I r 2 � R 2
For points outside the wire (r � R)
Magnetic field, B _ = _ 0 I 2 � R
_ B B _ = _ 0 I ( a / 2 ) 2 � a 2 _ 0 I 2 � ( 2 a ) = 1 : 1