What is the magnitude of an electric field that balances the weight of a plastic sphere of mass 2.1 g that has been charged to -3.0 nC? A)7.8 x 10^5 N/C B)1.5 x 10^6 N/C C)2.1 x 10^6 N/C D)6.9 x 10^6 N/C

Assume the charged objects in Figure OQ23.10 are fixed. Notice that there is no sight line from the location of q2 to the location of q1. If you were at q1, you would be unable to see q2 because it is behind q3. How would you calculate the electric force exerted on the object with charge q1? (a) Find only the force exerted by q2 on charge q1. (b) Find only the force exerted by q3 an charge q1. (c) Add the force that q2 would exert by itself on charge q1 to the force that q3 would exert by itself on charge q1. (d) Add the force that q3 would exert by itself to a certain fraction of the force that q2 would exert by itself. (e) There is no definite way to find the force on charge q1.

This afternoon, you have a physics symposium class, and you are the presenter. You will be presenting a topic to physics majors and faculty. You have been so busy that you have not had time to prepare and you dont even have an idea for a topic. You are frantically reading your physics textbook looking for an idea. In your reading, you have learned that the Earth carries a charge on its surface of about 105 C, which results in electric fields in the atmosphere. This gets you very excited about a new theory. Suppose the Moon also carries a charge on the order of 105 C, with the opposite sign! Maybe the orbit of the Moon around the Earth is due to electrical attraction between the Moon and the Earth! Theres an idea for your symposium presentation! You quickly jot down a few notes and run off to your symposium. While you are speaking, you notice one of the professors doing some calculations on a scrap of paper. Uh-oh! He has just raised his hand with a question. Why are you embarrassed?

(a) Find the magnitude and direction of the electric field at the position of the 2.00 C charge in Figure P13.13. (b) How would the electric field at that point be affected if the charge there were doubled? Would the magnitude of the electric force be affected?

Figure 24.10 shows a source that consists of two charged particles. a. What is the sign of the charge on each particle? b. In which region (A, B, or C) is the electric field the weakest? c. In which region (A, B, or C) is the electric field the strongest? FIGURE 24.10

Rank the magnitudes of the electric field at points A, B, and C in Figure 15.15, with the largest magnitude first. (a) A, B, C (b) A, C, B (c) C, A, B (d) The answer cant be determined by visual inspection. Figure 15.15 The electric field lines for two positive point charges. The points A, B, and C are discussed in Quick Quiz 15.6.

(a) Using the symmetry of the arrangement, show that the electric field at the center of the square in figure 18.46 is zero if the charges on the four comers are exactly equal. (b) Show that this is also true for any combination of charges in which qa= qd and qa = qc

A common demonstration involves charging a rubber balloon, which is an insulator, by rubbing it on your hair and then touching the balloon to a ceiling or wall, which is also an insulator. Because of the electrical attraction between the charged balloon and the neutral wall, the balloon slicks to the wall. Imagine now that we have two infinitely large, Hat sheets of insulating material. One is charged, and the other is neutral, lf these sheets are brought into contact, does an attractive force exist between them as there was for the balloon and the wall?

A test charge of +3 C is at a point P where an external electric field is directed to the right and has a magnitude of 4 06 N/C. If the test charge is replaced with another charge of 3 C, what happens to the external electric field at P? (a) It is unaffected. (b) It reverses direction. (c) It changes in a way that cannot be determined.

Earth has a net charge that produces an electric field of approximately 150 N/C downward at its surface. (a) What is the magnitude and sign of the excess charge, noting the electric field of a conducting sphere is equivalent to a point charge at its center? (b) What acceleration will the field produce on a free electron near Earth’s surface? (c) What mass object with a single extra electron will have its weight supported by this field?