Question

What is the magnetic field at point O?
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Answer 1

Answer:

Magnetic field by Biot Savart law,

dB=

4π

μ

0

r

2

idlsinθ

Due to the straight wires, θ=0 i.e. it lies on the same line as the centre.

Due to curved portion, lets consider infinitesimal length dl where dl and R are always at 90 degree.

Hence dB=

4π

μ

0

R

2

idl

Integrating from 0 to πR

dB=

4R

μ

0

i

hope you will be understood:)

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