18. A metal sphere of radius R is given a positive charge Q. What is the electric field at a distance r from the center,where r> R?A. Q/nE,r?B. Q/4nE,R?C. Q/4nEor?D. Q/nE,R?19. A positive charge of 4.0 µC exerts an attractive force of 8N on an unknown charge 20 cm away. The unknowncharge isA. + 8.9 µCB. - 8.9 µCC. +44. µCD. - 44. µC20. When you draw the direction of the electric field, you always use atest charge.A. neutralB. negativeC. positiveD. radioactive21. What is true in visualizing electric field lines of force from a charge body?A. Field lines are continuous curve and they never intersect.B. The spacing between these lines increases as they get far from the charged body.C. The number of field lines is directly proportional to the magnitude of the electric field.D. All of the above.22. If two identical charges are placed 4 m apart, what would the electric field be at the point directly between them?A. O N/CB. 2 N/CC. 8 N/CD. 16 N/C23. A region around a stationary electric charge hasC. Electromagnetic fieldD. Both electric and magnetic fieldA. Electric fieldB. Magnetic field24. A 2 C charge experiences a force of 40 N when put at a certain location in space. The electric field at that locationisA. 2 N/CB. 20 N/CC. 42 N/CD. 80 N/C25. Which of the following is NOT true about static charges?A. Like charges repel.B. Opposite charges attract.C. A negatively charged object has lost protonsD. A positively charged object has lost electrons.26. If you comb your hair and the comb becomes positively charged, then your hair becomesB. neutrally chargeC. positively charged D. unchargedA. negatively charged27. A negatively charged balloon is brought near a metal can that rests on a wood table. The side of the can oppositethe balloon is momentarily touched. The can is thenA. negatively chargedB. neutrally chargedC. positively chargedD. uncharged28. A neutral plastic strip is rubbed with cotton and acquires a positive charge. Which of the following statements isNOT true of the positively-charged strip?A. It has the opposite charge as the cotton.B. It lost some electrons to the cotton during the charging process.C. It has an excess of protons compared to the number of electrons.D. It would now be repelled by the piece of cotton which was used to charge it.29. Charge carriers in a metal are electrons rather than protons. This is due to the fact that electrons areA. LighterB. loosely boundC. far from a nucleusD. All of them30. If an electroscope, charged up with excess negative charge, is touched and grounded, then it will end up withcharge.A. negativeB. neutralC. pos iveD. none of them

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18. A metal sphere of radius R is given a positive charge Q. What is the electric field at a distance r from the center, where r> R? A. Q/nE,r? B. Q/4nE,R? C. Q/4nE,r? D. Q/nE,R? 19. A positive charge of 4.0 µC exerts an attractive force of 8N on an unknown charge 20 cm away. The unknown charge is A.+ 8.9 με B.-8.9 με C. + 44. µC D.- 44 με 20. When you draw the direction of the electric field, you always use a test charge. A. neutral B. negative C. positive D. radioactive

18. A metal sphere of radius R is given a positive charge Q. What is the electric field at a distance r from the center, where r> R? A. Q/nE,r? B. Q/4nE,R? C. Q/4nE,r? D. Q/nE,R? 19. A positive charge of 4.0 µC exerts an attractive force of 8N on an unknown charge 20 cm away. The unknown charge is A.+ 8.9 με B.-8.9 με C. + 44. µC D.- 44 με 20. When you draw the direction of the electric field, you always use a test charge. A. neutral B. negative C. positive D. radioactive

College Physics

1st Edition

ISBN:9781938168000

Author:Paul Peter Urone, Roger Hinrichs

Publisher:Paul Peter Urone, Roger Hinrichs

Chapter18: Electric Charge And Electric Field

Section: Chapter Questions

Problem 54PE: Earth has a net charge that produces an electric field of approximately 150 N/C downward at its...

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A long, straight metal rod has a radius of 5.00 cm and a charge per unit length of 30.0 nC/m. Find the electric field (a) 3.00 cm, (b) 10.0 cm. and (c) 100 cm from the axis of the rod, where distances are measured perpendicular to the rods axis.
A thin, square, conducting plate 50.0 cm on a side lies in the xy plane. A total charge of 4.00 108 C is placed on the plate. Find (a) the charge density on each face of the plate, (b) the electric field just above the plate, and (c) the electric field just below the plate. You may assume the charge density is uniform.
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?
(a) Using the symmetry of the arrangement, determine the direction of the electric field at the center of the square in Figure 18.53, given that qa= 1.00C and qc=qd= +1.00 C. (b) Calculate the magnitude of the electric field at the location of q, given that the square is 5.00 cm on a side.
A nonconducting, thin plane sheet of charge carries a uniform charge per unit area of 5.20 C/m2 as in Figure 15.30. (a) Find the electric field at a distance of 8.70 cm from the plate. (b) Explain whether your result changes as the distance from the sheet is varied.
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Refer 10 Figure 15.20. The charge lowered into the center of the hollow conductor has a magnitude of 5 C. Find the magnitude and sign of the charge on the inside and outside of the hollow conductor when the charge is as shown in (a) Figure 15.20a, (b) Figure 15.20b, (c) Figure 15.20c, and (d) Figure 15.20d.
(a) What magnitude point charge creates a 10,000 N/C electric field at a distance of 0.250 m? (b) How large is the field at 10.0 m?
The charge unit length on the thin shown below is .What is the force on the point charge q? Solve this problem by first considering the electric force dF on q due to a small segment dx of the rod, which contains charge dx . Then, find the net force by integrating dF over the length of the rod.
Suppose the conducting spherical shell of Figure 15.29 carries a charge of 3.00 nC and that a charge of -2.00 nC is at the center of the sphere. If a = 2.00 m and b = 2.40 m. find the electric field at (a) r = 1.50 m, (b) r = 2.20 m, and (c) r = 2.50 m. (d) What is the charge distribution on the sphere?
A uniformly charged disk of radius 35.0 cm carries charge with a density of 7.90 10-3 C/m2. Calculate the electric field on the axis of the disk at (a) 5.00 cm, (b) 10.0 cm, (c) 50.0 cm, and (d) 200 cm from the center of the disk.
(a) Two point charges q1 and q23.00 m apart, and their total charge is 20 C. (a) If the force of repulsion between them is 0.075N, what are magnitudes of the two charges? (b) If one charge attracts the other with a force of 0.150 N, what are the magnitudes of the two charges? Note that you may need to solve a quadratic equation to reach your answer.