Exam 28: Magnetic Fields

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 * 10⁵ m/s and v_y = 3 * 10⁵ m/s. A magnetic field of 0.8 T is in the positive x direction. At that instant the magnitude of the magnetic force on the electron is:

The diagrms show five possible orientations of a magnetic dipole in a uniform magnetic field For which of these is the potential energy the greatest?

An electron and a proton both each travel with equal speeds around circular orbits in the same uniform magnetic field, as shown in the diagram (not to scale). The field is into the page on the diagram. Because the electron is less massive than the proton and because the electron is negatively charged and the proton is positively charged:

An electron travels due north through a vacuum in a region of uniform magnetic field that is also directed due north. It will:

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 *10⁵ m/s and v_y = 3 *10⁵ m/s. A magnetic field of 0.8 T is in the positive x direction. At that instant the magnitude of the magnetic force on the electron is:

An electron is launched with velocity in a uniform magnetic field The angle $\theta$ between is between 0 and 90^o. As a result, the electron follows a helix, its velocity vector returning to its initial value in a time interval of:

A uniform magnetic field is in the positive z direction. A positively charged particle is moving in the positive x direction through the field. The net force on the particle can be made zero by applying an electric field in what direction?

A magnetic field CANNOT: