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AP EAMCET · PHYSICS · Magnetic Effects of Current

A circular coil connected to a battery of emf E produced a certain magnetic induction field at its centre. The coil is unwound, stretched to double its length rewound into a coil of 1rd3 of the original radius and connected to a battery of emf E' to produce same field at the centre. Then E' is

  1. A 2E9
  2. B 3E7
  3. C 9E4
  4. D 7E4
Verified Solution

Answer & Solution

Correct Answer

(A) 2E9

Step-by-step Solution

Detailed explanation

The expression for the magnetic field at the centre of a circular coil of n turns. B=μ0i2rn If length of the wire is doubled, 2 2πrn=2πr'n' 2 r n=r3n' n'=6n For the same field at the centre, μ0in2r=μ0i'n'2r'…