Two infinitely long, thin, insulated, straight wires lie in the x-y plane along the x- and y- axis respectively. Each wire carries a current I, respectively in the positive x-direction and positive y-direction. The magnetic field will be zero at all points on the straight line:

Options

A. `y=x`
B. `y=-x`
C. `y=x-1`
D. `y=-x+1`

Answer

A

Explanation

If a wire carriers current along positive `x`-axis, then the magnetic field due to it along the line `y=x` in first quadrant is upwards. If a wire carriers current along positive `y`-axis, then the magnetic field due to it along the line `y=x` in first quadrant is downwards along the line `y=x`, above two values of magnetic field are equal ion magnitude but opposite in direction and thus, their resultant is zero.