अभिकथन (A): एक चल कुंडली गैल्वेनोमीटर (moving coil galvanometer) में विक्षेप (deflection) उसमें से प्रवाहित होने वाली धारा के सीधे आनुपातिक होता है। कारण (R): चल कुंडली गैल्वेनोमीटर की कुंडली को एक समान त्रिज्यीय चुंबकीय क्षेत्र (uniform radial magnetic field) में लटकाया जाता है।

A charged particle is released from rest in a region of space where steady and uniform electric and magnetic fields are parallel to each other. The particle will move in a:

Two very long, straight, parallel wires carry steady currents I and 2I in the same direction. The distance between the wires is d. At a certain instant, a point charge q is at a point equidistant from the two wires in the plane of the wires. Its instantaneous velocity v is perpendicular to this plane. The magnitude of the magnetic force acting on the charge at this instant is: