PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Magnetism and Electromagnetism · Magnetism and Electromagnetism
Problem
Three particles—an electron (q1=−e), a proton (q2=+e) and an alpha particle (q3=+2e)—are projected simultaneously with the same speed v into a uniform magnetic field B directed along the y-axis. Their initial velocity vectors lie in the x–z plane and make angles of 0∘, 60∘ and 120∘ with the positive x-axis, respectively.
(a) For each particle, state whether the magnitude of the magnetic force is zero, minimum non-zero, or maximum. Give reasons in each case.
(b) Compare qualitatively the directions of the magnetic forces acting on the three particles at the instant of entry.
(c) If the speed of the particles is doubled while all other conditions remain the same, explain how the answers to parts (a) and (b) will change, if at all.