Clayton State University Department of Natural Sciences April 2, 2014 Physics 2212 – Quiz 7 Name ____________________________________ 1. In a 1.32 T magnetic field directed vertically upward, a particle having a charge of magnitude 8.50μC and initially moving northward at 4.72 km/s is deflected toward the east. a. Is the particle charged positively or negatively? Positively – the particle obeys the right hand rule. b. Find the magnitude of the magnetic force on the particle. F | q | VB sin 0.0530 N 2. An electron is traveling horizontally toward the north in a uniform magnetic field that is directed vertically downward. In what direction does the magnetic force act on the electron? a. Upward. b. North. c. East. d. Downward. e. West. f. South. Clayton State University Department of Natural Sciences April 9, 2014 Physics 2212 – Quiz 8 Name __SOLUTION__________________________________ A cyclotron is to accelerate protons to energy of 5.4 MeV. The superconducting electromagnet of the cyclotron produces a 2.9-T magnetic field perpendicular to the proton orbits. Note: the mass of a proton is 1.67262178 × 10-27 kg. a. When the protons have achieved a kinetic energy of 2.7 MeV, what is the radius of their circular orbit? K 2.7 10 6 eV 4.32 10 13 J V 2K 2.27 10 7 m / s m b. What is their angular speed? V / r 2.775 10 7 rad / s where r 0.0818 m c. When the protons have achieved a kinetic energy of 5.4MeV, what is the radius of their circular orbit? V 2K 3.2110 7 m / s m r 0.116 m d. What is their angular speed now? V / r 2.775 10 7 rad / s e. What is the orbital period of these protons at this energy? T 2 0.227 10 7 s Clayton State University Department of Natural Sciences April 23, 2014 Physics 2212 – Quiz 9 Name ____SOLUTION________________________________ 1. A coil lies flat on a tabletop in a region where the magnetic field vector points straight up. The magnetic field vanishes suddenly. When viewed from above, what is the direction of the induced current in this coil as the field fades? a. Clockwise then counter-clockwise. b. Clockwise. c. Counter-clockwise then clockwise. d. Counter-clockwise. e. There is no current induced in the coil. 2. A circular metal ring is situated above a long straight wire, as shown in the figure. The straight wire has a current flowing to the right, and the current is increasing in time at a constant rate. Which statement is true? a. There is an induced current in the metal ring, flowing in a counter-clockwise direction. b. There is an induced current in the metal ring, flowing in a clockwise direction. (Continued on the next page.) c. There is no induced current in the metal ring because the current in the wire is changing at a constant rate. 3. The figure shows a bar magnet moving vertically upward toward a horizontal coil. The poles of the bar magnets are labeled X and Y. As the bar magnet approaches the coil it induces an electric current in the direction indicated on the figure (counter-clockwise as viewed from above). What are the correct polarities of the magnet? a. X is a south pole, Y is a north pole. b. Both X and Y are south poles. c. X is a north pole, Y is a south pole. d. Both X and Y are north poles. e. The polarities of the magnet cannot be determined from the information given. Department of Natural Sciences Clayton State University May 5, 2014 Physics 2212 – Quiz 10 Name __SOLUTION___________________________________ A series ac circuit contains a 50.0- resistor, a 15.0-F capacitor, a 0.200-H inductor, and a 60.0-Hz generator that has an rms output of 90.0 V. a. Find the impedance of the circuit. X L 2fL (2 )(60 Hz)(0.200 H ) 75.4 XC 1 1 176.8 2fC (2 )(60 Hz)(15.0 10 6 F ) Z R 2 ( X L X C ) 2 113 b. Find the maximum current that flows in the resistor. Vm I m Z I m Vm / Z 1.125 A c. Find the maximum potential difference across the capacitor. Vm I m X C 199 V d. Does the voltage lead the current in the circuit or the current leads the voltage? EXPLAIN. Current leads the voltage since the phase angle is negative.