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JEE · NEET Previous Year Question

$The magnetic field at a distance r from a long wire carrying current i is 0.4 tesla. The magnetic field at a distance 2 r is$

Topic: NEET PYQ

Answer: A. Full step-by-step solution below.

A $0.2 tesla$
B $0.8 tesla$
C $0.1 tesla$
D $1.6 tesla.$

Correct answer: A

Solution

(a) B = \frac{μ _{0} i}{2 πr} or B \propto \frac{1}{r} When r is doubled, the magnetic field becomes halved i.e. now the magnetic field will be 0.2 T.

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