A point charge travels due east at

PHYSICS · Subjective · AP · Physics 2: Algebra-based · Magnetism and Electromagnetism · Magnetism and Electromagnetism

Problem

+4.0\,\mu\text{C}

point charge travels due east at

3.0\times10^6\,\text{m/s}

. A

+1.0\,\mu\text{C}

test charge is located

0.040\,\text{m}

due south of the source charge. The region also contains a uniform electric field of magnitude

1.8\times10^3\,\text{N/C}

directed due south. The test charge will move due west. Take

\mu_0 = 4\pi\times10^{-7}\,\text{T}\cdot\text{m/A}

. Determine the speed the test charge must have so that the magnetic and electric forces on it exactly cancel.