The magnetic field at the origin due to the current flowing in the wire is

Options

A. `-(mu_0I)/(8pia)(hati+hatk)`
B. `(mu_0I)/(2pia)(hati+hatk)`
C. `(mu_0I)/(8pia)(-hati+hatk)`
D. `-(mu_0I)/(4piasqrt2) (hati-hatk)`

Answer

C

Explanation

(c)
`B_(OD)=0`
`B_(OB)=0`
`B_(AB)=(mu_0I)/(4piasqrt2)[cos45^@(-hati)+cos 45^@hatk]`
`(mu_0I)/(8pia)(-hati+hatk)`