Chapter #25 Solutions - University Physics with Modern Physics Volume 2 (Chapters 21-40) - Gary Westfall, Wolfgang Bauer - 2nd Edition

1cc. If the diameter of the wire in Example 25.2 is doubled, its resistance willa) increase by a factor of 4.b) increase by a factor of 2.c) stay the same.d) decrease by a factor of 2.e) decrease by a factor of 4.Example 25.2 Resistance of a Copper Wire... Get solution

1mcq. If the current through a resistor is increased by a factor of 2, how does this affect the power that is dissipated?a) It decreases by a factor of 4.b) It increases by a factor of 2.c) It decreases by a factor of 8.d) It increases by a factor of 4. Get solution

2cc. If the temperature of a copper wire with a resistance of 100Ω is increased by 25 K, the resistance willa) increase by approximately 10Ω.b) increase by approximately 4 mΩ .c) decrease by approximately 4 mΩ .d) decrease by approximately 10Ω .e) stay the same. Get solution

2mcq. You make a parallel connection between two resistors, resistor A having a very large resistance and resistor B having a very small resistance. The equivalent resistance for this combination will bea) slightly greater than the resistance of resistor A.b) slightly less than the resistance of resistor A.c) slightly greater than the resistance of resistor B.d) slightly less than the resistance of resistor B. Get solution

3cc. What are the relative magnitudes of the two resistances in Figure 25.13?a) R1 R2b) R1 = R2c) R1 > R2d) Not enough information is given in the figure to compare the resistances.Figure 25.13 (a) Conventional representation of a simple circuit with two resistors in series and a source of emf. (b) Three-dimensional representation of the same circuit, displaying the potential at each point in the circuit. The current in the circuit is shown for both views.... Get solution

3mcq. Two cylindrical wires, 1 and 2, made of the same material, have the same resistance. If the length of wire 2 is twice that of wire 1, what is the ratio of their cross-sectional areas, A1 and A2?a) A1/A2 = 2b) A1/A2 = 4c) A1/A2 = 0.5d) A1/A2 = 0.25 Get solution

4cc. Three identical resistors, R1, R2, and R3, are wired together as shown in the figure. An electric current is flowing through the three resistors. The current through R2...a) is the same as the current through R1 and R3.b) is a third of the current through R1 and R3.c) is twice the sum of the current through R1 and R3.d) is three times the current through R1 and R3.e) cannot be determined. Get solution

4mcq. All three light bulbs in the circuit shown in the figure are identical. Which of the three shines the brightest?a) Ab) Bc) Cd) A and Be) All three are equally bright.... Get solution

5cc. Three identical resistors, R1, R2, and R3, are wired together as shown in the figure. An electric current is flowing from point A to point B. The current flowing through R2...a) is the same as the current through R1 and R3.b) is a third of the current through R1 and R3.c) is twice the sum of the current through R1 and R3.d) is three times the current through R1 and R3.e) cannot be determined. Get solution

5mcq. All of the six light bulbs in the circuit shown in the figure are identical. Which ordering correctly expresses the relative brightness of the bulbs? (Hint: The more current flowing through a light bulb, the brighter it is!)a) A = B > C = D > E = Fb) A = B = E = F > C = Dc) C = D > A = B = E = Fd) A = B = C = D = E = F... Get solution

6cc. Which combination of resistors has the highest equivalent resistance?(a) ...(b) ...(c) ...(d) ...a) combination (a)b) combination (b)c) combination (c)d) combination (d)e) The equivalent resistance is the same for all four. Get solution

6mcq. Which of the arrangements of three identical light bulbs shown in the figure draws the most current from the battery?A ...B ...C. ...a) Ab) Bc) Cd) All three draw equal current.e) A and C are tied for drawing the most current. Get solution

7cc. As more identical resistors, R, are added to the circuit shown in the figure, the resistance between points A and B will...a) increase.b) stay the same.c) decrease.d) change in an unpredictable manner. Get solution

7mcq. Which of the arrangements of three identical light bulbs shown in the figure has the highest resistance?A ...B ...C. ...a) Ab) Bc) Cd) All three have equal resistance.e) A and C are tied for having the highest resistance. Get solution

8cc. Three light bulbs are connected in series with a battery that delivers a constant potential difference, Vemf. When a wire is connected across light bulb 2 as shown in the figure, light bulbs 1 and 3...a) burn just as brightly as they did before the wire was connected.b) burn more brightly than they did before the wire was connected.c) burn less brightly than they did before the wire was connected.d) go out. Get solution

8mcq. Three identical light bulbs are connected as shown in the figure. Initially the switch is closed. When the switch is opened (as shown in the figure), bulb C goes off. What happens to bulbs A and B?...a) Bulb A gets brighter, and bulb B gets dimmer.b) Both bulbs A and B get brighter.c) Both bulbs A and B get dimmer.d) Bulb A gets dimmer, and bulb B gets brighter. Get solution

9mcq. Which of the following wires has the largest current flowing through it?a) a 1-m-long copper wire of diameter 1 mm connected to a 10-V batteryb) a 0.5-m-long copper wire of diameter 0.5 mm connected to a 5-V batteryc) a 2-m-long copper wire of diameter 2 mm connected to a 20-V batteryd) a 1-m-long copper wire of diameter 0.5 mm connected to a 5-V batterye) All of the wires have the same current flowing through them. Get solution

10mcq. Ohm’s Law states that the potential difference across a device is equal toa) the current flowing through the device times the resistance of the device.b) the current flowing through the device divided by the resistance of the device.c) the resistance of the device divided by the current flowing through the device.d) the current flowing through the device times the cross-sectional area of the device.e) the current flowing through the device times the length of the device. Get solution

11mcq. A constant electric field is maintained inside a semiconductor. As the temperature is lowered, the magnitude of the current density inside the semiconductora) increases.b) stays the same.c) decreases.d) may increase or decrease. Get solution

12mcq. Which of the following is an incorrect statement?a) The currents through electronic devices connected in series are equal.b) The potential drops across electronic devices connected in parallel are equal.c) More current flows across the smaller resistance when two resistors are connected in parallel.d) More current flows across the smaller resistance when two resistors are connected in series. Get solution

13mcq. Identical batteries are connected in three different arrangements to the same light bulb as shown in the figure. Assume that the batteries have no internal resistance. In which arrangement will the light bulb shine the brightest?A ...B. ...C. ...a) Ab) Bc) Cd) The bulb will have the same brightness in all three arrangements.e) The bulb will not light in any of the arrangements. Get solution

14mcq. Identical batteries are connected in three different arrangements to the same light bulb as shown in the figure. Assume that the batteries have no internal resistance. In which arrangement will the light bulb shine the brightest?A. ...B. ...C. ...a) Ab) Bc) Cd) The bulb will have the same brightness in all three arrangements.e) The bulb will not light in any of the arrangements. Get solution

15cq. What would happen to the drift velocity of electrons in a wire if the resistance due to collisions between the electrons and the atoms in the crystal lattice of the metal disappeared? Get solution

16cq. Why do light bulbs typically burn out just as they are turned on rather than while they are lit? Get solution

17cq. Two identical light bulbs are connected to a battery. Will the light bulbs be brighter if they are connected in series or in parallel? Get solution

18cq. Two resistors with resistances R1 and R2 are connected in parallel. Demonstrate that, no matter what the actual values of R1 and R2 are, the equivalent resistance is always less than the smaller of the two resistances. Get solution

20cq. For the connections shown in the figure, determine the current i1 in terms of the total current, i, and R1 and R2.... Get solution

21cq. An infinite number of resistors are connected in parallel. If R1 = 10 Ω, R2 = 102 Ω, R3 = 103 Ω, and so on, show that Req = 9 Ω. Get solution

23cq. Should light bulbs (ordinary incandescent bulbs with tungsten filaments) be considered ohmic resistors? Why or why not? How would this be determined experimentally? Get solution

24cq. A charged-particle beam is used to inject a charge, Q0, into a small, irregularly shaped region (not a cavity, just some region within the solid block) in the interior of a block of ohmic material with conductivity σ and permittivity ε at time t = 0. Eventually, all the injected charge will move to the outer surface of the block, but how quickly?a) Derive a differential equation for the charge, Q(t), in the injection region as a function of time.b) Solve the equation from part (a) to find Q(t) for all t ≥ 0.c) For copper, a good conductor, and for quartz (crystalline SiO2), an insulator, calculate the time for the charge in the injection region to decrease by half. Look up the necessary values. Assume that the effective “dielectric constant’’ of copper is 1.00000. Get solution

25cq. Show that the drift speed of free electrons in a wire does not depend on the cross-sectional area of the wire. Get solution

26cq. Rank the brightness of the six identical light bulbs in the circuit in the figure. Each light bulb may be treated as an identical resistor with resistance R.... Get solution

27cq. Two conductors of the same length and radius are connected to the same emf device. If the resistance of one is twice that of the other, to which conductor is more power delivered? Get solution

28. How many protons are in the beam traveling close to the speed of light in the Tevatron at Fermilab, which is carrying 11 mA of current around the 6.3-km circumference of the main Tevatron ring? Get solution

29. What is the current density in an aluminum wire having a radius of 1.00 mm and carrying a current of 1.00 mA? What is the drift speed of the electrons carrying this current? The density of aluminum is 2.70·103 kg/m3, and 1 mole of aluminum has a mass of 26.98 g. There is one conduction electron per atom in aluminum. Get solution

30. A copper wire has a diameter dCu = 0.0500 cm, is 3.00 m long, and has a charge-carrier density of 8.50·1028 electrons/m3. As shown in the figure, the copper wire is attached to an equal length of aluminum wire with a diameter dAl = 0.0100 cm and a charge-carrier density of 6.02·1028 electrons/m3. A current of 0.400 A flows through the copper wire.a) What is the ratio of the current densities in the two wires, JCu/JAl?b) What is the ratio of the drift velocities in the two wires, vd–Cu/vd–Al?... Get solution

31. A current of 0.123 mA flows in a silver wire whose cross-sectional area is 0.923 mm2.a) Find the density of electrons in the wire, assuming that there is one conduction electron per silver atom.b) Find the current density in the wire assuming that the current is uniform.c) Find the electrons’ drift speed. Get solution

32. What is the resistance of a copper wire of length l = 10.9 m and diameter d = 1.30 mm? The resistivity of copper is 1.72·10–8 Ω m. Get solution

33. Two conductors are made of the same material and have the same length L. Conductor A is a hollow tube with inside diameter 2.00 mm and outside diameter 3.00 mm; conductor B is a solid wire with radius RB. What value of RB is required for the two conductors to have the same resistance measured between their ends?... Get solution

34. A copper coil has a resistance of 0.100 Ω at room temperature (20.0 °C). What is its resistance when it is cooled to –100. °C? Get solution

35. What gauge of aluminum wire will have the same resistance per unit length as 12-gauge copper wire? Get solution

36. A rectangular wafer of pure silicon, with resistivity ρ = 2300 Ω m, measures 2.00 cm by 3.00 cm by 0.0100 cm. Find the maximum resistance of this rectangular wafer between any two faces. Get solution

37. A copper wire that is 1.00 m long and has a radius of 0.500 mm is stretched to a length of 2.00 m. What is the fractional change in resistance, ∆R/R, as the wire is stretched? What is ∆R/R for a wire of the same initial dimensions made out of aluminum? Get solution

38. The most common material used for sandpaper, silicon carbide, is also widely used in electrical applications. One common device is a tubular resistor made of a special grade of silicon carbide called arborundum. A particular carborundum resistor (see the figure) consists of a thick-walled cylindrical shell (a pipe) of inner radius a = 1.50 cm, outer radius b = 2.50 cm, and length L = 60.0 cm. The resistance of this carborundum resistor at 20.0 °C is 1.00 Ω.a) Calculate the resistivity of carborundum at room temperature. Compare this to the resistivities of the most commonly used conductors (copper, aluminum, and silver).b) Carborundum has a high temperature coefficient of resistivity: α = 2.14·10–3 K–1. If, in a particular application, the carborundum resistor heats up to 300. °C, what is the percentage change in its resistance between room temperature (20.0 °C) and this operating temperature?... Get solution

39. As illustrated in the figure, a current, i, flows through the junction of two materials with the same cross-sectional area and with conductivities σ1 and σ2. Show that the total amount of charge at the junction is ε0i(1/ σ2 – 1/ σ1).... Get solution

40. A potential difference of 12.0 V is applied across a wire of crosssectional area 4.50 mm2 and length 1000. km. The current passing through the wire is 3.20 · 10–3 A.a) What is the resistance of the wire?b) What type of wire is this? Get solution

41. One brand of 12.0-V automotive battery used to be advertised as providing “600 cold-cranking amps.” Assuming that this is the current the battery supplies if its terminals are shorted, that is, connected to negligible resistance, determine the internal resistance of the battery. (IMPORTANT: Do not attempt such a connection as it could be lethal!) Get solution

42. A copper wire has radius r = 0.0250 cm, is 3.00 m long, has resistivity ρ = 1.72·10–8 Ω m, and carries a current of 0.400 A. The wire has a charge-carrier density of 8.50·1028 electrons/m3.a) What is the resistance, R, of the wire?b) What is the electric potential difference, ∆V, across the wire?c) What is the electric field, E, in the wire? Get solution

43. A 34-gauge copper wire (A = 0.0201 mm2), with a constant potential difference of 0.100 V applied across its 1.00 m length at room temperature (20.0 °C), is cooled to liquid nitrogen temperature (77 K = –196 °C).a) Determine the percentage change in the wire’s resistance during the drop in temperature.b) Determine the percentage change in current flowing in the wire.c) Compare the drift speeds of the electrons at the two temperatures. Get solution

44. A resistor of unknown resistance and a 35.0-Ω resistor are connected across a 120.-V emf device in such a way that an 11.0-A current flows. What is the value of the unknown resistance? Get solution

45. A battery has a potential difference of 14.50 V when it is not connected in a circuit. When a 17.91-Ω resistor is connected across the battery, the potential difference of the battery drops to 12.68 V. What is the internal resistance of the battery? Get solution

46. When a battery is connected to a 100.-Ω resistor, the current is 4.00 A. When the same battery is connected to a 400.-Ω resistor, the current is 1.01 A. Find the emf supplied by the battery and the internal resistance of the battery. Get solution

47. A light bulb is connected to a source of emf. There is a 6.20 V drop across the light bulb and a current of 4.10 A flowing through the light bulb.a) What is the resistance of the light bulb?b) A second light bulb, identical to the first, is connected in series with the first bulb. The potential drop across the bulbs is now 6.29 V, and the current through the bulbs is 2.90 A. Calculate the resistance of each light bulb.c) Why are your answers to parts (a) and (b) not the same? Get solution

48. What is the current in the 10.0-Ω resistor in the circuit in the figure?... Get solution

49. What is the equivalent resistance of the five resistors in the circuit in the figure?... Get solution

50. What is the current in the circuit shown in the figure when the switch is (a) open and (b) closed?... Get solution

51. For the circuit shown in the figure, R1 = 6.00 Ω, R2 = 6.00 Ω, R3 = 2.00 Ω, R4 = 4.00 Ω, R5 = 3.00 Ω, and the potential difference is 12.0 V.a) What is the equivalent resistance for the circuit?b) What is the current through R5?c) What is the potential drop across R3?... Get solution

52. Four resistors are connected in a circuit as shown in the figure. What value of R1, expressed as a multiple of R0, will make the equivalent resistance for the circuit equal to R0?... Get solution

53. As shown in the figure, a circuit consists of an emf source with V = 20.0 V and six resistors. Resistors R1 = 5.00 Ω and R2 = 10.00 Ω are connected in series. Resistors R3 = 5.00 Ω and R4 = 5.00 Ω are connected in parallel and are in series with R1 and R2. Resistors R5 = 2.00 Ω and R6 = 2.00 Ω are connected in parallel and are also in series with R1 and R2.a) What is the potential drop across each resistor?b) How much current flows through each resistor?... Get solution

54. When a 40.0-V emf device is placed across two resistors in series, a current of 10.0 A flows through each of the resistors. When the same emf device is placed across the same two resistors in parallel, the current through the emf device is 50.0 A. What is the magnitude of the larger of the two resistances? Get solution

55. A voltage spike causes the line voltage in a home to jump rapidly from 110. V to 150. V. What is the percentage increase in the power output of a 100.-W tungsten-filament incandescent light bulb during this spike, assuming that the bulb’s resistance remains constant? Get solution

56. A thundercloud similar to the one described in Example 24.3 produces a lightning bolt that strikes a radio tower. If the lightning bolt transfers 5.00 C of charge in about 0.100 ms and the potential remains constant at 70.0 MV, find (a) the average current, (b) the average power, (c) the total energy, and (d) the effective resistance of the air during the lightning strike.Example 24.3 Thundercloud...... Get solution

57. A hair dryer consumes 1600. W of power and operates at 110. V. (Assume that the current is DC. In fact, these are root-mean-square values of AC quantities, but the calculation is not affected. Chapter 30 covers AC circuits in detail.)a) Will the hair dryer trip a circuit breaker designed to interrupt the circuit if the current exceeds 15.0 A?b) What is the resistance of the hair dryer when it is operating? Get solution

58. How much money will a homeowner owe an electric company if he turns on a 100.00-W incandescent light bulb and leaves it on for an entire year? (Assume that the cost of electricity is $0.12000/kWh and that the light bulb lasts that long.) The same amount of light can be provided by a 26.000-W compact fluorescent light bulb. What would it cost the homeowner to leave one of those on for a year? Get solution

59. Three resistors are connected across a battery as shown in the figure.a) How much power is dissipated across the three resistors?b) Determine the potential drop across each resistor.... Get solution

60. Suppose an AAA battery is able to supply 625 mAh before its potential drops below 1.50 V. How long will it be able to supply power to a 5.00-W bulb before the potential drops below 1.50 V? Get solution

61. Show that the power supplied to the circuit in the figure by the battery with internal resistance Ri is maximum when the resistance of the resistor in the circuit, R, is equal to Ri. Determine the power supplied to R. For practice, calculate the power dissipated by a 12.0-V battery with an internal resistance of 2.00 Ω when R = 1.00 Ω, R = 2.00 Ω, and R = 3.00 Ω.... Get solution

62. A water heater consisting of a metal coil that is connected across the terminals of a 15.0-V power supply is able to heat 250 mL of water from room temperature to boiling point in 45.0 s. What is the resistance of the coil? Get solution

63. A potential difference of V = 0.500 V is applied across a block of silicon with resistivity 8.70·10–4 Ω m. As indicated in the figure, the dimensions of the silicon block are width a = 2.00 mm and length L = 15.0 cm. The resistance of the silicon block is 50.0 Ω, and the density of charge carriers is 1.23·1023 m–3. Assume that the current density in the block is uniform and that current flows in silicon according to Ohm’s Law. The total length of 0.500-mm-diameter copper wire in the circuit is 75.0 cm, and the resistivity of copper is 1.69 ·10–8 Ω m.a) What is the resistance, Rw, of the copper wire?b) What are the direction and the magnitude of the electric current, i, in the block?c) What is the thickness, b, of the block?d) On average, how long does it take an electron to pass from one end of the block to the other?e) How much power, P, is dissipated by the block?f) As what form of energy does this dissipated power appear?... Get solution

64. In an emergency, you need to run a radio that uses 30.0 W of power when attached to a 10.0-V power supply. The only power supply you have access to provides 25.0 kV, but you do have a large number of 25.0- Ω resistors. If you want the power to the radio to be as close as possible to 30.0 W, how many resistors should you use, and how should they be connected (in series or in parallel)? Get solution

65. A certain brand of hot dog cooker applies a potential difference of 120. V to opposite ends of the hot dog and cooks it by means of the heat produced. If 48.0 kJ is needed to cook each hot dog, what current is needed to cook three hot dogs simultaneously in 2.00 min? Assume a parallel connection. Get solution

66. A circuit consists of a copper wire of length 10.0 m and radius 1.00 mm connected to a 10.0-V battery. An aluminum wire of length 5.00 m is connected to the same battery and dissipates the same amount of power. What is the radius of the aluminum wire? Get solution

67. The resistivity of a conductor is ρ = 1.00 ·10–5 Ω m. If a cylindrical wire is made of this conductor, with a cross-sectional area of 1.00·10–6 m2, what should the length of the wire be for its resistance to be 10.0 Ω? Get solution

68. Two cylindrical wires of identical length are made of copper and aluminum. If they carry the same current and have the same potential difference across their length, what is the ratio of their radii? Get solution

69. Two resistors with resistances 200. Ω and 400. Ω are connected (a) in series and (b) in parallel with an ideal 9.00-V battery. Compare the power delivered to the 200.- Ω resistor. Get solution

70. What are (a) the conductance and (b) the radius of a 3.50-m-long iron heating element for a 110.-V, 1500.-W heater? Get solution

71. A 100.-W, 240.-V European light bulb is used in an American household, where the electricity is delivered at 120. V. What power will it consume? Get solution

72. A modern house is wired for 115 V, and the current is limited by circuit breakers to a maximum of 200. A. (For the purpose of this problem, treat these as DC quantities.)a) Calculate the minimum total resistance the circuitry in the house can have at any time.b) Calculate the maximum electrical power the house can consume. Get solution

73. A 12.0-V battery with an internal resistance Ri = 4.00 Ω is attached across an external resistor of resistance R. Find the maximum power that can be delivered to the resistor. Get solution

74. A multiclad wire consists of a zinc core of radius 1.00 mm surrounded by a copper sheath of thickness 1.00 mm. The resistivity of zinc is ρ = 5.964·10–8 Ω m. What is the resistance of a 10.0-m-long strand of this wire? Get solution

75. The Stanford Linear Accelerator accelerated a beam consisting of 2.0·1014 electrons per second through a potential difference of 2.0·1010 V.a) Calculate the current in the beam.b) Calculate the power of the beam.c) Calculate the effective ohmic resistance of the accelerator. Get solution

76. In the circuit shown in the figure, R1 = 3.00 Ω, R2 = 6.00 Ω, R3 = 20.0 Ω, and Vemf = 12.0 V.a) Determine a value for the equivalent resistance.b) Calculate the magnitude of the current flowing through R3 on the top branch of the circuit (marked with a vertical arrow).... Get solution

77. Three resistors are connected to a power supply with V = 110. V as shown in the figure.a) Find the potential drop across R3.b) Find the current in R1.c) Find the rate at which thermal energy is dissipated from R2.... Get solution

78. A battery with V = 1.500 V is connected to three resistors as shown in the figure.a) Find the potential drop across each resistor.b) Find the current in each resistor.... Get solution

79. A 2.50-m-long copper cable is connected across the terminals of a 12.0-V car battery. Assuming that it is completely insulated from its environment, how long aft er the connection is made will the copper start to melt? (Useful information: copper has a mass density of 8960 kg/m3, a melting point of 1359 K, and a specific heat of 386 J/kg/K.) Get solution

80. A piece of copper wire is used to form a circular loop of radius 10.0 cm. The wire has a cross-sectional area of 10.0 mm2. Points A and B are 90.0° apart, as shown in the figure. Find the resistance between points A and B.... Get solution

81. Two conducting wires have identical lengths L1 = L2 = L = 10.0 km and identical circular cross sections of radius r1 = r2 = r = 1.00 mm. One wire is made of steel (with resistivity ρsteel = 40.0 · 10–8 Ω m); the other is made of copper (with resistivity ρcopper = 1.68 · 10–8 Ω m).a) Calculate the ratio of the power dissipated by the two wires, Pcopper/Psteel, when they are connected in parallel and a potential difference of V = 100. V is applied to them.b) Based on this result, how do you explain the fact that conductors for power transmission are made of copper and not steel? Get solution

82. Before bendable tungsten filaments were developed, Thomas Edison used carbon filaments in his light bulbs. Though carbon has a very high melting temperature (3599 °C), its sublimation rate is high at high temperatures. So carbon-filament bulbs were kept at lower temperatures, thereby rendering them dimmer than later tungsten-based bulbs. A typical carbon-filament bulb requires an average power of 40. W, when 110 volts is applied across it, and has a filament temperature of 1800 °C. Carbon, unlike copper, has a negative temperature coefficient of resistivity: α = –0.00050 °C–1. Calculate the resistance at room temperature (20. °C) of this carbon filament. Get solution

83. A material is said to be ohmic if an electric field, ... in the material gives rise to current density ... =...,where the conductivity, σ is a constant independent of ... or ... (This is the precise form of Ohm’s Law.) Suppose in some material an electric field, ... produces current density, ... not necessarily related by Ohm’s Law; that is, the material may or may not be ohmic.a) Calculate the rate of energy dissipation (sometimes called ohmic heating or joule heating) per unit volume in this material, in terms of ... and ...b) Express the result of part (a) in terms of ... alone and ...alone, for ...and ... related via Ohm’s Law, that is, in an ohmic material with conductivity σ or resistivity ρ. Get solution

84. A high-voltage direct current (HVDC) transmission line carries electrical power a distance of 643.1 km. The line transmits 7935 MW of power at a potential difference of 1.177 MV. If the HVDC line consists of one copper wire of diameter 2.353 cm, what fraction of the power is lost in transmission? Get solution

85. A high-voltage direct current (HVDC) transmission line carries 5319 MW of electrical power a distance of 411.7 km. The HVDC line consists of one copper wire of diameter 2.125 cm. The fraction of the power lost in transmission is 7.538·10–2. What is the potential difference in the line? Get solution

86. A high-voltage direct current (HVDC) transmission line carries 5703 MW of electrical power at a potential difference of 1.197 MV. The HVDC line consists of one copper wire of diameter 1.895 cm. The fraction of the power lost in transmission is 1.166 · 10–1. How long is the line? Get solution

87. The reserve capacity (RC) of a car battery is defined as the number of minutes the battery can provide 25.0 A of current at a potential difference of 10.5 V. Thus, the RC indicates how long the battery can power a car whose charging system has failed. How much energy is stored in a car battery with an RC of 110.0? Get solution

88. The reserve capacity (RC) of a car battery is defined as the number of minutes the battery can provide 25.0 A of current at a potential difference of 10.5 V. Thus, the RC indicates how long the battery can power a car whose charging system has failed. If a car battery stores 1.843·106 J of energy, what is its RC? Get solution

89. A flashlight bulb with a tungsten filament draws 374.3 mA of current when a potential difference of 3.907 V is applied. When the bulb is at room temperature (20.00 °C) and is not lit, its resistance is 1.347 Ω. What is the temperature of the tungsten filament when the bulb is lit? Get solution

90. A flashlight bulb with a tungsten filament draws 420.1 mA when a potential difference of 3.949 V is applied. The temperature of the tungsten filament when the bulb is lit is 1291 °C. What is the resistance of the bulb when it is at room temperature (20.00 °C) and is not lit? Get solution

91. When a flashlight bulb with a tungsten filament is lit, the applied potential difference is 3.991 V and the temperature of the tungsten filament is 1.110·103 °C. The resistance of the bulb when it is at room temperature (20.00 °C) and is not lit is 1.451 Ω. What current does the bulb draw when it is lit? Get solution


Chapter #40 Solutions - University Physics with Modern Physics Volume 2 (Chapters 21-40) - Gary Westfall, Wolfgang Bauer - 2nd Edition

1cc. Which isotope X is needed to complete the reaction ...a) ...b) ...c) ...d) ...e) ... Get solution 1mcq. Radium-226 decays by e...