Question

A wire carrying I and other carrying 2 I in the same direction produce a magnetic field B at the mid­point. What will be the field when 2 I wire is switched off?

Answer 1

Answer:

1) 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 [AFMC 2005]

A) B / 2

B) 2B

C) B

D) 48

Correct Answer: C

Solution :

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 \[B=\frac{{{\mu }_{0}}I}{2\pi r}\].

Answer 2

Answer:

I don't know the answer:)

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