PHYS 122 Midterm: Phys122Fall2014Exam3LectureMC
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Use the following scenario for the next three questions. A positively charged ion with a velocity v and mass m enters a square region of uniform magnetic field with magnitude b pointing into the page. The ion enters at the middle of one side as shown. 2ql: this cannot be achieved, (5 points) suppose you now apply a uniform electric field to the magnetic field region and observed that the ion travels in a straight path. What is the magnitude and direction of the electric field that you applied: qvb , pointing up, vb , pointing up, qvb , pointing down, vb , pointing down. Consider an operation of a simple dc motor as shown; a current flows in a loop of wire in a uniform magnetic field. Which of the following is the magnitude of the torque on the loop when the potential energy stored in the system of the loop and the applied field is the maximum: bia.
