Question

Rank the value of $\oint \overrightarrow{B}\cdot \overrightarrow{\mathrm{dI}}$ for the closed paths shown in figure from the smallest to largest.

• A. $a,b,c,d$
• B. $a,c,d,b$
• C. $a,d,c,b$
• D. $a,c,b,d$

Answer 1

Answer: (B)

Use $\oint \overrightarrow{B}\cdot \overline{d1}={\mu }_0{I}_{enclosed}$
Net current enclosed by path $a$ a is zero
Net current enclosed by path $c$ is $A$
Net current enclosed by path $d$ is $3A$
Net current enclosed by path $b$ is $5A$