PHYSICS · Multi-part · Fermi University Physics · Electricity, Magnetism & Electromagnetism · Electric current and circuits · Magnetostatics
Electricity, Magnetism and Electromagnetism, Ch The Biot-Savart law and the fields of steady currents
Problem
A flat metal strip lies in the xy-plane. Its length runs along x, its width is w=12mm along y, and its small thickness is along z. A steady conventional current flows along +x; the carriers are electrons of charge −e (e=1.602×10−19C) which therefore drift along −x with a steady speed vd=5.9×10−4ms−1. A uniform magnetic field B=0.45T along +z fills the strip. Charge piles up along the two long edges until the transverse electric field it makes exerts on each drifting electron a force that exactly cancels the transverse magnetic force, after which the drift is again straight along the strip. Assume this transverse field is uniform across the width, so that the potential difference between the edges is (transverse field) ×w. Gravity and the field of the current itself are ignored.
((a)) Find the magnitude of the magnetic force on one drifting electron, and say which edge (y positive or y negative) the electrons are pushed towards.
((b)) Find the magnitude of the steady transverse electric field, and state its direction.
((c)) Find the potential difference between the two edges, and say which edge is at the higher potential.