An arc of a circle of raduis `R` subtends an angle `(pi)/2` at the centre. It carriers a current `i`. The magnetic field at the centre will be

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An arc of a circle of raduis `R` subtends an angle `(pi)/2` at the centre. It carriers a current `i`. The ... (0)i)/(4R)` D. `(2mu_(0)i)/(5R)`

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