Axis of a solid cylinder of infinite length and radius R lies along y-axis. It carries a uniformly distributed current I along +y direction. Magnetic field at a point `(R//2, y, R//2)` is

Options

A. `(mu_(0)i)/(4piR)(hati-hatk)`
B. `(mu_(0)i)/(2piR)(hatj-hatk)`
C. `(mu_(0)i)/(4piR)hatj`
D. `(mu_(0)i)/(4piR)(hati+hatk)`

Answer

A

Explanation

`B=((mu_(0)i)/(piR^(2))xxpi(R/sqrt2)^(2))/(2pisqrt2R/2)[cos45^(@) hati-cos 45^(@) hatk]`
`=(mu_(0)i^(2))/(4piR)(hati-hatk)`