In a sketch of an evacuated tube

PHYSICS · Multi-part · Fermi University Physics · Mathematical Methods for Physics · Electricity, Magnetism & Electromagnetism · Vector calculus and field geometry

Electricity, Magnetism and Electromagnetism, Ch The Biot-Savart law and the fields of steady currents

Problem

In a sketch of an evacuated tube, one arrow shows the velocity of an electron: it lies in the xzxz-plane, has magnitude 2.0×106 m s−12.0\times10^{6}\,\mathrm{m\,s^{-1}} and points at 40∘40^\circ above the +x+x axis, turned towards +z+z. A second arrow shows a uniform magnetic field of magnitude 0.15 T0.15\,\mathrm{T} along +y^+\hat{\mathbf{y}}. The electron has charge −e-e; gravity is ignored. ((a)) Write v\mathbf{v} and B\mathbf{B} in components. ((b)) Evaluate v×B\mathbf{v}\times\mathbf{B} in components. ((c)) Give the magnetic force F=qv×B\mathbf{F} = q\mathbf{v}\times\mathbf{B} on the electron in components and its magnitude, and say which plane it lies in.

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