A hairpin like shape as shown in figure is made by bending a long current carrying wire. What is the magnitude of a magnetic field at point $P$ which lies on the centre of the semicircle ?
A$\frac{\mu_{0} I }{4 \pi r }(2-\pi)$
B$\frac{\mu_{0} I }{4 \pi r }(2+\pi)$
C$\frac{\mu_{0} I }{2 \pi r }(2+\pi)$
D$\frac{\mu_{0} I }{2 \pi r }(2-\pi)$
JEE MAIN 2021, Diffcult
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B$\frac{\mu_{0} I }{4 \pi r }(2+\pi)$
b $B =2 \times B _{ \text { straight.wire }}+ B _{\text {loop }}$
$B =2 \times \frac{\mu_{0} i }{4 \pi r }+\frac{\mu_{0} i }{2 r }\left(\frac{\pi}{2 \pi}\right)$
$B =\frac{\mu_{0} i }{4 \pi r }(2+\pi)$
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