At one instant an electron (charge = -1.6 *10^-19C) is moving in the xy plane, the components of its velocity being v_x = 5.0 *10⁵ m/s and v_y = 3.0 * 10⁵ m/s. A magnetic field of 0.80 T is in the positive y direction. At that instant the magnitude of the magnetic force on the electron is: A) 0 N B) 3.8 * 10^-14 N C) 6.4 * 10^-14 N D) 7.5 *10^-14 N E) 1.0 * 10^-14

Question

Quizplus · Accepted Answer

The magnetic force on a charged particle is given by F = q(v × B). Here, the velocity component v_y is parallel to the magnetic field, so it does not contribute to the force. Only v_x contributes, and the force is F = |q|v_xB = (1.6 × 10^-19 C)(5.0 × 10⁵ m/s)(0.80 T) = 6.4 × 10^-14 N.

At One Instant an Electron (Charge = -1