Question

As shown in the figure, a long straight conductor with semicircular are of radius $\frac{\pi}{10} m$ is carrying current $I =3 A$ The magnitude of the magnetic field at the center $O$ of the arc is :(The permeability of the vacuum $=4 \pi \times 10^{-7} NA ^{-2}$ )

• A. $6 \mu T$
• B. $4 \mu T$
• C. $3 \mu T$
• D. $1 \mu T$

Answer 1

Answer: (C)

$3 \mu T$

Answer 2

BC​=4πRμ0​I​(π)(B at centre of circular arc )
=4Rμ0​I​=4×10π​4π×10−7×3​
=3×10−6T=3μT