Quiz 9 Fall 2011

1. For magnets, like poles repel each other and unlike poles A. also repel each other. B. attract each other. C. can attract or repel each other. D. neither attract nor repel each other. E. disappear into nothingness.

2. Surrounding moving electric charges are A. electric fields. B. magnetic fields. C. both of these D. none of these

3. The magnetic field lines about a current-carrying wire form A. circles. B. radial lines. C. spirals. D. some combination of these E. None of these

4. A magnetic force acts most strongly on a current-carrying wire when it A. carries a weak current perpendicular to a weak magnetic field. B. carries a very large current parallel to a weak magnetic field. C. carries a very large current parallel to a strong magnetic field. D. None of these

5. A magnetic force acting on a beam of electrons can change A. only the direction of the beam. B. only the energy of the electrons. C. both the direction and the energy. D. neither the direction nor the energy.

6. Voltage will be induced in a wire loop when a magnetic field within that loop A. changes with time. B. is constant with time. C. is parallel to the electric field. D. is perpendicular to the electric field. E. converts to magnetic energy.

7. The essential physics concept in an electric generator is A. Coulomb’s law. B. Ohm’s law. C. Faraday’s law. D. Newton’s second law. E. None of these

8. When a generator is used to light a lamp, the energy of the lit lamp originates in the A. coils of wire in the generator. B. magnet inside the generator. C. lamp itself. D. work done to turn the coils in the generator. E. None of these

9. A step-down transformer has a greater number of coils on the A. input side. B. output side. C. side with lower power. D. side with the higher power. E. more than one of these.

10. A changing electric field can induce a changing A. current loop. B. voltage. C. power. D. magnetic field.

Answer key 1. B 2. C 3. A 4. A 5. A 6. A 7. C 8. D 9. A 10. D