The dipole moment of a circular loop carrying a current I , is m and the magnetic field at the centre of the loop is B 1 . When the dipole moment is doubled by keeping the current constant, the magnetic field at the centre of the loop is B

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The dipole moment of a circular loop carrying a current I , is m and the magnetic field at the centre of the loop is B 1 . When the dipole moment is doubled by keeping the current constant, the magnetic field at the centre of the loop is B 2 . The ratio B 1 B 2 is:

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Correct answer: D. 2

m = magnetic dipole moment = I A . For L o o p 1 , m = I &#960; r 2 , B 1 = &#956; 0 i 2 r For L o o p 2 . If current is constant m is doubled. r 1 = 2 r . B 2 = &#956; 0 i 2 2 r . B 1 B 2 = 2

The dipole moment of a circular loop carrying a current I , is m and the magnetic field at the centre of the loop is B 1 . When the dipole moment is doubled by keeping the current constant, the magnetic field at the centre of the loop is B 2 . The ratio B 1 B 2 is:

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