A positively charged particle of charge travels due east at constant speed in…
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Magnetism and Electromagnetism · Magnetism and Electromagnetism
Problem
A positively charged particle of charge +qs travels due east at constant speed vs in otherwise empty space. At the instant shown, point P is located a distance d due south of the particle.
A small test charge is placed at P. Ignore any electric interaction between the two charges; consider only magnetic effects.
(a) Identify the direction of the magnetic field at point P produced by the moving source charge.
(b) The test charge is positive and is given an instantaneous velocity due north (toward the source charge). Determine the direction of the magnetic force that acts on the test charge at that instant.
(c) If, instead, the test charge were negative but had the same northward velocity, how would the direction of the magnetic force change? State the new direction explicitly.
(d) Explain your reasoning clearly for parts (a)–(c), referencing the relevant vector relationships among the source-charge velocity, the position vector from the source charge to P, and the test-charge velocity.