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_0iqv)/(2pid)`
B. `(mu_0iqv)/(pid)`
C. `(3mu_0iqv)/(2pid)`
D. zero.

Answer

D

Explanation

(d) Magnetic field at P is perpendicular to paper inward due
to both the wires. Charged particle is also projected in the
same direction. So, force on the charged particle is zero as
`vecv||vecB and vecF_m=q(vecvxxvecB)`