Two very long straight parallel wire carry steay currents i. and 2i in opposite directions . The disatance between the waire is d . At a certain instant of time a point charge q is at a point equadistant from the two wires in the plane of the wires . Its instantaneous velocity v is perpendicular to this plane . The magnetude of the magnetic field acting on the charge at this isntant 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)`