Concept explainers
An electrophorus is a device developed more than 200 years ago for the purpose of charging objects. The insulator on top of a pedestal is rubbed with a cloth, such as wool (Fig. P23.18A). A conductor is placed on top of the insulator, and the conductor is connected to ground by a
Want to see the full answer?
Check out a sample textbook solutionChapter 23 Solutions
Webassign Printed Access Card For Katz's Physics For Scientists And Engineers: Foundations And Connections, 1st Edition, Single-term
- (a) What is the final speed of an electron accelerated from rest through a voltage of 25.0 MV by a negatively charged Van de Graff terminal? (b) What is unreasonable about this result? (c) Which assumptions are responsible?arrow_forwardTwo small metallic spheres, each with a mass of 2.00 g, are suspended from a common point by two strings of negligible mass and of length 10.0 cm. When the spheres have an equal amount of charge, the two strings make an Figure P23.67arrow_forwardThis 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 don’t 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! There’s 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?arrow_forward
- Two square plates of sides { are placed parallel to each other with separation d as suggested in Figure P26.65. You may assume d is much less than €. The plates carry uniformly distributed static charges +Q. and -Qo. Á block of metal has width €, length €, and thickness slightly less than d. It is inserted a distance x into the space between the plates. The charges on the plates remain uniformly distributed as the block slides in. In a static situation, a metal prevents an electric field from penetrating inside it. The metal can be thought of as a perfect dielectric, withK - 0. (a) Calculate the stored energy in the system as a function of x. (b) Find the direction and magnitude of the force that acts on the metallic block. (c) The area of the advancing front face of the block is essen- tially equal to ld. Considering the force on the block as acting on this face, find the stress (force per area) on it. (d) Express the energy density in the electric field between the charged plates in…arrow_forward21.96 0. Two charges are placed as shown in Fig. P21.96. The magnitude of q1 is 3.00 µC, but its sign and the value of the charge q2 are not known. Figure P21.96 P 5.0 cm 12.0 cm The direction of the net electric field E É at point P is entirely in the negative y-direction. (a) Considering the different possible signs of q1 and q2, four possible diagrams could represent the electric fields Ej and E produced by q1 and q2. Sketch the four possible electric- field configurations. (b) Using the sketches from part (a) and the direction of E, deduce the signs of q1 and q2. (c) Determine the magnitude of E. 91 13.0 cm 92arrow_forwardmh.2arrow_forward
- 21.96 **. Two charges are placed as Figure P21.96 shown in Fig. P21.96. The magnitude of qi is 3.00 µC, but its sign and the value of the charge q2 are not known. The direction of the net electric field É at point P is entirely in the negative y-direction. (a) Considering the different possible signs of q1 and q2, four possible diagrams could represent the electric fields Ēj and É2 produced by q1 and 92. Sketch the four possible electric- field configurations. (b) Using the sketches from part (a) and the direction of É, deduce the signs of q1 and q2. (c) Determine the magnitude of E. P 5.0 cm 12.0 cm 13.0 cm 92arrow_forwardYou are working in a biology lab during your summer break. Your supervisor asks you to perform an experiment to find the effective spring constant (in N/m) of a partial molecule of DNA (deoxyribonucleic acid). You perform experiments and find that a single straight portion of a DNA molecule is 2.32 µm long. You then perform an activity that charges the ends of the molecule; each end becomes singly ionized: negative on one end, positive on the other. After the ends are charged, the molecule shrinks by 1.25% of its length. Use the particle in equilibrium model to balance the electric and elastic forces on a particle at one of the ends of the molecule. N/marrow_forwardAn electron is fired at a speed v0 = 5.6 ×106 m/s and at an angle θ0 =−45° between two parallel conducting plates that are D = 2.0 mm apart, as in Figure P16.72. If the voltage difference between the plates is ΔV = 100. V, determine (a) how close, d, the electron will get to the bottom plate and (b) where the electron will strike the top plate.arrow_forward
- You are working in a manufacturing plant. In one particular machine, electric charges are suspended above a uniformly charged disk of radius R. The disks become corroded rapidly and must be replaced daily. Your supervisor comes to you one day and tells you that he wants to replace the disks with much cheaper washers of radius R with a concentric hole of radius R/4. He asks you to determine by what factor the charge on the disk must be increased so that a uniform charge on the washer would provide the same electric field at a distance x = R on the central axis as did the disk Answer should be in the form qwasher/qdiskarrow_forwardTo see why, compute the force of Earth’s gravity on an electron and compare it with the force exerted on the electron by an electric field of magnitude 14000 V/m (a relatively small field). Express your answer to two significant figures and include the appropriate units.arrow_forwardFlying insects such as bees may accumulate a small positive electric charge as they fly. In one experiment, the mean electric charge of 50 bees was measured to be ++(30 ±± 5) pCpC per bee. Researchers also observed the electrical properties of a plant consisting of a flower atop a long stem. The charge on the stem was measured as a positively charged bee approached, landed, and flew away. Plants are normally electrically neutral, so the measured net electric charge on the stem was zero when the bee was very far away. As the bee approached the flower, a small net positive charge was detected in the stem, even before the bee landed. Once the bee landed, the whole plant became positively charged, and this positive charge remained on the plant after the bee flew away. By creating artificial flowers with various charge values, experimenters found that bees can distinguish between charged and uncharged flowers and may use the positive electric charge left by a previous bee as a cue…arrow_forward
- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage LearningPhysics for Scientists and Engineers with Modern ...PhysicsISBN:9781337553292Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning