Question

Figure shows two idertical current i and an amperian icops encrading them. The value of $\oint B.dl$ is

• A. $-{\mu }_{0}i$
• B. $-{2\mu }_{0}i$
• C. Zero
• D. $-\frac{{\mu }_{0}i}{2}$

Answer 1

The correct option is B $-{2\mu }_{0}i$

Given : Figure shows two idertical current i and an amperian icops encrading them.

Solution :

Let us consider loop 1 in which current is flowing outside and loop 2 in which current is flowing inside.

$\oint B.dl=-\mu I_{enc}$

Net $I_{enc}$=$2i$ as loop2 is opposite of loop 1 so the minus sign due to opposite current will cancel out.

Substituting value in the formula we get $\oint B.dl=-2\mu i$

The Correct opt :B