Two long straight wires are set parallel to each other. Each carriers a current `i` in the same direction and the separation between them is `2r`. The intensity of the magnetic field midway between them is

Options

A. Zero
B. `(mu_(0)i)/(4piR)`
C. `(mu_(0)i)/(2piR)`
D. `(mu_(0)i)/(piR)`

Answer

D

Explanation

`B=(mu_(0)i)/(2piR)+(mu_(0)i)/(2piR)=(mu_(0)i)/(piR)`