Home › ISC Class 12 › Physics › Moving Charges and Magnetism › Two long parallel wires carry currents in the sa…
Two long parallel wires carry currents in the same direction. The force between them is:
AAttractive
BRepulsive
CZero
DAlways perpendicular to both
Answer & Solution
Correct answer: A. Attractive
1. Each wire sits in the magnetic field of the other.
2. Applying $\mathbf{F} = I\mathbf{l}\times\mathbf{B}$ to each wire gives forces directed toward the other wire.
3. Hence parallel (same-direction) currents attract.
4. Antiparallel currents would instead repel, so the zero/perpendicular options are wrong.
_Source: NCERT Class 12 Physics Ch 4 "Moving Charges and Magnetism", p.154_
Related questions
An electron and a proton enter a magnetic field with the same kinetic energy, perpendiculaA galvanometer is converted into an ammeter of higher range by connecting:The work done by a static magnetic force on a moving charge is:Magnetic field at a point on the axis of a circular loop, far from the loop (distance x ≫ The dimensional formula of the magnetic field B (in SI units of tesla) is:A cyclotron of magnetic field B accelerates positive charges of mass m, charge q. The cyclTorque on a magnetic dipole (current loop) of moment m placed in a uniform field B at anglTwo long parallel wires carry currents I₁ and I₂ in the SAME direction, separated by dista