Two very long straight parallel wires carry steady currents `i` and `2i` in opposite directions. The distance between the wires is `d`. At a certain instant of time a point charge `q` is at a point equidistant from the two wires in the plane of the wires. Its instantaneous velocity `vecv` is perpendicular to this plane. The magnitude of the force due to the magnetic field acting on t he charge at this instant is

Options

A. `(mu_(0)iqv)/(2pid)`
B. `(mu_(0)iqv)/(pid)`
C. `(3mu_(0)iqv)/(2pid)`
D. zero

Answer

D

Explanation

Magnetic field `P` is perpendicular to paper inwards due to both the wires. Charged particle is also projected in the same direction. So force on charged particle is zero
As `vecv||vecB` and `vecF_(m)=q(vecvxxvecB)`