Question

A straight wire carrying current of 13 A is bent into a semi-circular arc of radius 2 cm as shown in figure. The magnetic field is $1.5\times {10}^{-4}T$ at the centre of arc, then the magnetic field due to straight segment is

• A. $1.5\times {10}^{-4}T$
• B. $2.5\times {10}^{-4}T$
• C. zero
• D. $3.5\times {10}^{-4}T$

Answer 1

Answer: (C)

zero

Since $dl$ and r for each element of the straight segments are parallel. Therefore
$\overrightarrow{dl}\times \overrightarrow{r}=0$
Hence, B is also zero.