Q. Two very long, straight, parallel wires carry steady current $i\ \ and - i$ resepectively. 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 magnitude of the force due to the magnetic field acting on the charge at this instant is
A) $\frac{\mu_{0}iqv}{2\pi d}$
B) $\frac{\mu_{0}iqv}{\pi d}$
C) $\frac{2\mu_{0}\ iqv}{\pi d}$
D) zero
Explanation
(d) Since, the currents are flowing in the opposite directions, the magnetic field at a point equidistant from the two wires will be zero. Hence, the force acting on the charge at this instant will be zero.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.