A wire carrying current $I$ and other carrying $2I$ in the same direction produces a magnetic field $B$ at the mid point. What will be the field when $2I$ wire is switched off
A$B / 2$
B$2B$
C$B$
D$4B$
Medium
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C$B$
c (c) When two parallel conductors carrying current $I$ and $2I $ in same direction, then magnetic field at the midpoint is
$B = \frac{{{\mu _0}2l}}{{2\pi r}} - \frac{{{\mu _0}I}}{{2\pi r}} = \frac{{{\mu _0}I}}{{2\pi r}}$
When current $2I$ is switched off then magnetic field due to conductor carrying current $I$ is $B = \frac{{{\mu _0}I}}{{2\pi r}}$.
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