Clayton College & State University Department of Natural Sciences September 2, Physics 1112 Quiz 1. Name SOLUTION

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1 Clayton College & State University September 2, 2004 Name SOLUTION 1. Three non-conducting balls supported by insulating threads hang from a support. We know that ball X is positively charged. When ball X is brought near balls Y and Z without touching them, it attracts Y and repels Z. We can conclude that a. Y has a negative charge. b. Z has a negative charge. c. Y is neutral. d. Z is neutral. 2. Doug rubs a piece of fur on a hard rubber rod, giving the rod a negative charge. What happens? a. Protons are removed from the rod. b. Electrons are added to the rod. c. The fur is also charged negatively. d. The fur is left neutral. 3. A metal sphere is grounded and a positively charged balloon is brought near it. The switch is opened and the balloon is taken away. The sphere is now a. Neutral. b. Negatively charged. c. Positively charged. d. Charged, but we cannot know its polarity.

2 Aug 27, 2007 Name SOLUTION 1. Electrons carry a a. Positive charge. b. Negative charge. c. Neutral charge. d. Variable charge. 2. The units of Coulomb s constant are? a. Nm 2 /C 2. b. Nm. c. Nm/C 2. d. C Two charges, Q 1 and Q 2, are separated by a certain distance R. If the magnitudes of the charges are doubled, and their separation is halved, then what happens to the electrical force between these charges? a. It increases by a factor of 16. b. It increases by a factor of 8. c. It is doubled. d. It remains the same. Clayton State University

3 January 19, 2006 Name SOLUTION 1. Is it possible for two negative charges to attract each other? a. Yes, they always attract. b. Yes, they will attract if they are closer enough. c. Yes, they will attract if one carries a larger charge than the other. d. No, they will never attract. 2. An atom has more electrons than protons. The atom is a. A positive ion. b. A negative ion c. A neutral atom d. Impossible 3. A negatively charged rod is brought near one end of an uncharged metal bar. The end of the metal bar farthest from the charged rod will be charged a. Positive. b. Negative. c. Neutral. d. None of the above. Clayton State University January 16, 2007

4 Name SOLUTION 1. One important difference between conductors and insulators is that a. Conductors can conduct electricity and insulators conduct heat. b. Conductors can conduct heat and insulators can conduct electricity. c. Conductors can conduct heat as well as electricity but insulators cannot conduct heat or electricity. d. Conductors cannot conduct heat as well as electricity but insulators can conduct heat or electricity. 2. Two objects, A and B, are rubbed together. As a result, object A acquires an excessive negative charge while object B becomes positively charged. In comparison with their masses before the charging process, you can say that a. The mass of both objects increased. b. The mass of A increased and the mass of B decreased. c. The mass of A decreased and the mass of B increased. d. The mass of both objects decreased. 3. Electrical and gravitational forces follow similar equations with one main difference: a. Electrical force obeys the inverse square law and gravitational force does not. b. Gravitational force obeys the inverse square law and electrical force does not. c. Electrical force is attractive and gravitational force is repulsive. d. Gravitational force is always attractive but electric force can be either attractive or repulsive.

5 January 15, 2008 Name SOLUTION 1. Neutrons carry a. Positive charge. b. Negative charge. c. No charge. d. Variable charge. 2. The units of the permittivity of free space, 0, ( hint: k = 1 4 ) are? 0 a. Nm 2 /C 2. b. C 2 / (Nm 2 ). c. Nm/C 2. d. C Two charges, Q 1 and Q 2, are separated by a certain distance R. If the magnitudes of the charges are tripled, but their separation distance remains the same, then what happens to the electrical force between these charges? a. It increases by a factor of 9. b. It increases by a factor of 6. c. It increases by a factor of 3. d. It remains the same.

6 June 5, 2006 Name SOLUTION 1. A glass rod is rubbed with a piece of silk. During the process the glass rod acquires a positive charge and the silk a. Acquires a positive charge also. b. Acquires a negative charge. c. Remains neutral. d. Could either be positively charged or negatively charged. It depends on how hard the rod was rubbed. 2. A negatively charged rod is brought near one end of an uncharged metal bar. The end of the metal bar farthest from the charged rod will be charged a. Positive. b. Negative. c. Neutral. d. None of the given answers 3. An electron and a proton are separated by a distance of 1.00 m. What happens to the strength of the force on the proton if the electron is moved m closer to the proton? a. It increases to 4 times its original value. b. It increases to 2 times its original value. c. It decreases to one-half its original value. d. It decreases to one-fourth its original value. Clayton State University

7 May 31, 2007 Name SOLUTION 1. A charged rod carrying a negative charge is brought near two spheres that are in contact with each other but insulated from the ground. If the two spheres are then separated, what kind of charge will be on the spheres? a. The sphere near the charged rod becomes positive and the other becomes negative. b. The sphere near the charged rod becomes negative and the other becomes positive. c. Both spheres remain neutral. d. None of the other choices is correct. 2. By what method will a positively charged rod produce a negative charge on a conducting sphere placed on an insulating surface? a. By conduction. b. By induction. (If we are given a chance to ground the sphere, otherwise it is impossible.) c. By convection. d. It is impossible. 3. Two charges, Q 1 and Q 2, are separated by a certain distance R. If the magnitudes of the charges are halved, and their separation is also halved, then what happens to the electrical force between these charges? a. It increases by a factor of 8. b. It increases by a factor of 4. c. It is doubled. d. It remains the same.

8 May 29, 2008 Name SOLUTION 1. Protons carry a. Positive charge. b. Negative charge. c. No charge. d. Variable charge. 2. By what method will a negatively charged rod produce a positive charge on a conducting sphere placed on an insulating surface? a. By conduction. b. By induction. c. By convection. d. It is impossible. 3. Two charges, Q 1 and Q 2, are separated by a certain distance R. If the magnitudes of the charges remain the same, but their separation distance triples, then what happens to the electrical force between these charges? a. It increases by a factor of 9. b. It increases by a factor of 3. c. It decreases by a factor of 3. d. It decreases by a factor of 9.

9 October 14, 2009 Name SOLUTION 4. Three non-conducting balls supported by insulating threads hang from a support. We know that ball X is positively charged. When ball X is brought near balls Y and Z without touching them, it attracts Y and repels Z. We can conclude that e. Y has a negative charge. f. Z has a negative charge. g. Y is neutral. h. Z is neutral. 5. Doug rubs a piece of fur on a hard rubber rod, giving the rod a negative charge. What happens? e. Protons are removed from the rod. f. Electrons are added to the rod. g. The fur is also charged negatively. h. The fur is left neutral. 6. A metal sphere is grounded and a positively charged balloon is brought near it. The switch is opened and the balloon is taken away. The sphere is now e. Neutral. f. Negatively charged. g. Positively charged. h. Charged, but we cannot know its polarity.

10 August 23, 2010 Name SOLUTION 1. Protons carry a a. Positive charge. b. Negative charge. c. Neutral charge. d. Variable charge. 2. The units of Coulomb s constant are? a. Nm 2 /C 2. b. Nm. c. Nm/C 2. d. C Two charges, Q 1 and Q 2, are separated by a certain distance R. If the magnitudes of the charges are doubled, and their separation is halved, then what happens to the electrical force between these charges? a. It increases by a factor of 16. b. It increases by a factor of 4. c. It is doubled. d. It remains the same.

11 Should you have the current increasing or decreasing with time?