16. An electron moves through a magnetic eld :9" with a velocity 3, as shown. What direction does the magnetic force on the electron act in? Z X a. along the negative y-axis b. along the negative x-axis c along the positive zaxis d along the negative zaxis 17. A proton with a charge e feels a magnetic force F when moving through a magnetic eld. If the speed of the proton is doubled, what is the new magnetic force on the proton? a. 4F 13. 3F c. 2F d.F 18. An alpha particle has a charge of 2e. A proton moves through a magnetic field with a velocity v. The alpha particle moves through the same field in the same direction, and feels the same magnetic force. What is the velocity of the alpha particle? a. 2v b. C. 0.5V d. 0.25v 19. An electron moves through a magnetic field perpendicular to the field and feels a magnetic force of magnitude F. At what angle, relative to the field, will it feel a force of magnitude = F? a. go b. 30 C. 450 d. 600 20. A charge of 30.0 C flows through a segment of wire in 5.00 s. What is the current in the wire? a. 0.167 A b. 5.00 A C. 6.00 A d. 30.0 A21. A current of 5.00 A flows through a wire 10.0 cm long. The wire is in a magnetic field of strength 2.00 T, perpendicular to the wire. What is the magnitude of the magnetic force acting on the wire? a. ON b. 0.500 N C. 1.00 N d. 2.00 N 22. A segment of wire in a magnetic field carries a current and feels a magnetic force F. The strength of the field and the current are both doubled. What does the magnetic force become? a. F NAH b F C. 2F d. 4F23. 24. 25. A segment of wire carries a current in a magnetic eld as shown. What is the direction of the magnetic force on the wire? a. upward out of the page b. downward into the page c. toward the top of the page d. toward the bottom of the page The magnetic forces between current-carrying wires were rst measured by which scientist? a. Ampere b. Volta c. Coulomb d. Newton What is the energy change that takes place during the operation of a loudspeaker? a. electrical energy to magnetic energy b. magnetic energy to electrical energy c. electrical energy to sound energy (1. sound energy to electrical energy 26. Electromagnetic pumps are used to move fluids in kidneys and artificial hearts. What advantage do these pumps have over traditional mechanical pumps? a. electromagnetic pumps do not require a power source b. electromagnetic pumps do not damage blood cells c. mechanical pumps make too much noise d. mechanical pumps rely on an external source of energy 27. Mass spectrometers have many uses. What is an example of such a use? a. to define the elemental composition of a sample or molecule b. to determine the mass of a particle c. to reveal the chemical structure of a molecule d. all of these 28. What is the principle of a mass spectrometer? a. a magnetic field is used to deflect electrically charged particles b. an electric field is used to deflect electrically charged particles c. a magnetic field is used to deflect particles with mass d. an electric field is used to deflect particles with mass29. A particle with mass m and charge q is shot into a magnetic field B perpendicular to the field at a speed v. The particle moves in a circle with radius r. Which equation determines the radius of the circle? a. QVB b. myB 1 = C. T = d. 7 = 30. A proton and an alpha particle with four times the mass and twice the charge of the proton are shot into a magnetic field perpendicular to the field. How does the radius of the circular motion of the alpha particle compare to the radius of the circular motion of the proton? a. eight times the radius b. twice the radius c. half the radius d. one-eighth of the radius