College Physics 1st Edition
ISBN: 9781938168000
Author: Paul Peter Urone, Roger Hinrichs
Publisher: Paul Peter Urone, Roger Hinrichs
1 Introduction: The Nature Of Science And Physics 2 Kinematics 3 Two-dimensional Kinematics 4 Dynamics: Force And Newton's Laws Of Motion 5 Further Applications Of Newton's Laws: Friction, Drag, And Elasticity 6 Uniform Circular Motion And Gravitation 7 Work, Energy, And Energy Resources 8 Linear Momentum And Collisions 9 Statics And Torque 10 Rotational Motion And Angular Momentum 11 Fluid Statics 12 Fluid Dynamics And Its Biological And Medical Applications 13 Temperature, Kinetic Theory, And The Gas Laws 14 Heat And Heat Transfer Methods 15 Thermodynamics 16 Oscillatory Motion And Waves 17 Physics Of Hearing 18 Electric Charge And Electric Field 19 Electric Potential And Electric Field 20 Electric Current, Resistance, And Ohm's Law 21 Circuits And Dc Instruments 22 Magnetism 23 Electromagnetic Induction, Ac Circuits, And Electrical Technologies 24 Electromagnetic Waves 25 Geometric Optics 26 Vision And Optical Instruments 27 Wave Optics 28 Special Relativity 29 Introduction To Quantum Physics 30 Atomic Physics 31 Radioactivity And Nuclear Physics 32 Medical Applications Of Nuclear Physics 33 Particle Physics 34 Frontiers Of Physics Chapter20: Electric Current, Resistance, And Ohm's Law
Chapter Questions Section: Chapter Questions
Problem 1CQ: Can a wire carry a current and still be neutral-that is, have a total charge of zero? Explain. Problem 2CQ: Car batteries are rated in ampere-hours (A h ). To what physical quantity do ampere-hours... Problem 3CQ: If two different wires having identical cross-sectional areas carry the same current, will the drift... Problem 4CQ: Why are two conducting paths from a voltage source to an electrical device needed to operate the... Problem 5CQ: In cars, one battery terminal is connected to the metal body. How does this allow a single wire to... Problem 6CQ: Why isn't a bird sitting on a high-voltage power line electrocuted? Contrast this with the situation... Problem 7CQ: The IR drop across a resistor means that there is a change in potential or voltage across the... Problem 8CQ: How is the I R drop in a resistor similar to the pressure drop in a fluid flowing through a pipe? Problem 9CQ: In which of the three semiconducting materials listed in Table 20.1 do impurities supply free... Problem 10CQ: Does the resistance of an object depend on the path current takes through it? Consider, for example,... Problem 11CQ: If aluminum and copper wires of the same length have the same resistance, which has the larger... Problem 12CQ: Explain why R=R0(1 + a?T) for the temperature variation of the resistance R of an object is not as... Problem 13CQ: Why do incandescent lightbulbs grow dim late in their lives, particularly just before their... Problem 14CQ: The power dissipated in a resistor is given by P = V2/R, which means power decreases if resistance... Problem 15CQ: Give an example of a use of AC power other than in the household. Similarly, give an example of a... Problem 16CQ: Why do voltage, current, and power go through zero 120 times per second for 60-Hz AC electricity? Problem 17CQ: You are riding in a train, gazing into the distance through its window. As close objects streak by,... Problem 18CQ: Using an ohmmeter, a student measures the resistance between various points on his body. He finds... Problem 19CQ: What are the two major hazards of electricity? Problem 20CQ: Why isn’t a short circuit a shock hazard? Problem 21CQ: What determines the severity of a shock? Can you say that a certain voltage is hazardous without... Problem 22CQ: An electrified needle is used to burn off warts, with the circuit being completed by having the... Problem 23CQ: Some surgery is performed with high-voltage electricity passing from a metal scalpel through the... Problem 24CQ: Some devices often used in bathrooms, such as hairdryers, often have safety messages saying “Do not... Problem 25CQ: We are often advised to not flick electric switches with wet hands, dry your hand first. We are also... Problem 26CQ: Before working on a power transmission line, linemen will touch the line with the back of the hand... Problem 27CQ: Why is the resistance of wet skin so much smaller than dry, and why do blood and other bodily fluids... Problem 28CQ: Could a person on intravenous infusion (an IV) be microshock sensitive? Problem 29CQ: In view of the small currents that cause shock hazards and the larger currents that circuit breakers... Problem 30CQ: Note that in Figure 20.28, both the concentration gradient and the Coulomb force tend to move Na+... Problem 31CQ: Define depolarization, repolarization, and the action potential. Problem 32CQ: Explain the properties of myelinated nerves in terms of the insulating properties of myelin. Problem 1PE: What is the current in milliamperes produced by the solar cells of a pocket calculator through which... Problem 2PE: A total of 600 C of charge passes through a flashlight in 0.500 h. What is the average current? Problem 3PE: What is the current when a typical static charge of 0.250 C moves from your finger to a metal... Problem 4PE: Find the current when 2.00 nC jumps between your comb and hair over a 0.500-s time interval. Problem 5PE: A large lightning bolt had a 20,000-A current and moved 30.0 C of charge. What was its duration? Problem 6PE: The 200-A current through a spark plug moves 0.300 mC of charge. How long does the spark last? Problem 7PE: (a) A defibrillator sends a 6.00-A current through the chest of a patient by applying a 10,000-V... Problem 8PE: During open-heart surgery, a defibrillator can be used to bring a patient out of cardiac arrest. The... Problem 9PE: (a) A defibrillator passes 12.0 A of current through the torso of a person for 0.0100 s. How much... Problem 10PE: A clock battery wears out after moving 10,000 C of charge through the clock at a rate of 0.500 mA.... Problem 11PE: The batteries of a submerged non-nuclear submarine supply 1000 A at full speed ahead. How long does... Problem 12PE: Electron guns are used in X-ray tubes. The electrons are accelerated through a relatively large... Problem 13PE: A large cyclotron directs a beam of He ++ nuclei onto a target with a beam current of 0.250 mA. (a)... Problem 14PE: Repeat the above example on Example 20.3, but for a wire made of silver and given there is one free... Problem 15PE: Using the results of the above example on Example 20.3, find the drift velocity in a copper wire of... Problem 16PE: A 14-gauge copper wire has a diameter of 1.628 mm. What magnitude current flows when the drift... Problem 17PE: SPEAR, a storage ring about 72.0 m in diameter at the Stanford Linear Accelerator (closed in 2009),... Problem 18PE: What current flows through the bulb of a 3.00-V flashlight when its hot resistance is 3.60 O ? Problem 19PE: Calculate the effective resistance of a pocket calculator that has a 1.35-V battery and through... Problem 20PE: What is the effective resistance of a car’s starter motor when 150 A flows through it as the car... Problem 21PE: How many volts are supplied to operate an indicator light on a DVD player that has a resistance of... Problem 22PE: (a) F ind the voltage drop in an extension cord having a 0.0600-O resistance and through which 5.00... Problem 23PE: A power transmission line is hung from metal towers with glass insulators having a resistance of... Problem 24PE: What is the resistance of a 20.0-m-long piece of 12-gauge copper wire having a 2.053-mm diameter? Problem 25PE: The diameter of 0-gauge copper wire is 8.252 mm. Find the resistance of a 1.00-km length of such... Problem 26PE: If the 0.100-mm diameter tungsten filament in a light bulb is to have a resistance of 0.200at... Problem 27PE: Find the ratio of the diameter of aluminum to copper wire, if they have the same resistance per unit... Problem 28PE: What current flows through a 2.54-cm-diameter rod of pure silicon that is 20.0 cm long, when 1,00 ... Problem 29PE: (a) To what temperature must you raise a copper wire, originally at 20.0°C, to double its... Problem 30PE: A resistor made of Nichrome wire is used in an application where its resistance cannot change more... Problem 31PE: Of what material is a resistor made if its resistance is 40.0% greater at 100°C than at 20.0°C ? Problem 32PE: An electronic device designed to operate at any temperature in the range from -10.0°C to 55.0°C... Problem 33PE: a) Of what material is a wire made, if it is 25.0 m long with a 0.100 mm diameter and has a... Problem 34PE: Assuming a constant temperature coefficient of resistivity, what is the maximum percent decrease in... Problem 35PE: A wire is drawn through a die, stretching it to four times its original length. By what factor does... Problem 36PE: A copper wire has a resistance of 0.500at 20.0°C, and an iron wire has a resistance of 0.525at the... Problem 37PE: (a) Digital medical thermometers determine temperature by measuring the resistance of a... Problem 38PE: Integrated Concepts (a) Redo Exercise 20.25 taking into account the thermal expansion of the... Problem 39PE: Unreasonable Results (a) To what temperature must you raise a resistor made of constantan to double... Problem 40PE: What is the power of a 1.00 102 MV lightning boit having a current of 2.00 104 A ? Problem 41PE: What power is supplied to the starter motor of a large truck that draws 250 A of current from a... Problem 42PE: A charge of 4.00 C of charge passes through a pocket calculator’s solar cells in 4.00 h. What is the... Problem 43PE: How many watts does a flashlight that has 6.00102C pass through it in 0.500 h use if its voltage is... Problem 44PE: Find the power dissipated in each of these extension cords: (a) an extension cord having a 0,0600... Problem 45PE: Verify that the units of a volt-ampere are watts, as implied by the equation P =IV. Problem 46PE: Show that the units 1 V2/=1W , as implied by the equation P=V2/R . Problem 47PE: Show that the units 1 A 2 = 1W, as implied by the equation P=I 2 R. Problem 48PE: Verify the energy unit equivalence that 1 kWh = 3.60106 J. Problem 49PE: Electrons in an X-ray tube are accelerated through 1 .00 102 kV and directed toward a target to... Problem 50PE: An electric water heater consumes 5.00 kW for 2.00 h per day. What is the cost of running it for one... Problem 51PE: With a 1200-W toaster, how much electrical energy is needed to make a slice of toast (cooking time =... Problem 52PE: What would be the maximum cost of a CFL such that the total cost (investment plus operating) would... Problem 53PE: Some makes of older cars have 6.00-V electrical systems. (a) What is the hot resistance of a 30.0-W... Problem 54PE: Alkaline batteries have the advantage of putting out constant voltage until very nearly the end of... Problem 55PE: A cauterizer, used to stop bleeding in surgery, puts out 2.00 mA at 15.0 kV. (a) What is its power... Problem 56PE: The average television is said to be on 6 hours per day. Estimate the yearly cost of electricity to... Problem 57PE: An old lightbulb draws only 50.0 W, rather than its original 60.0 W, due to evaporative thinning of... Problem 58PE: -gauge copper wire has a diameter of 9.266 mm. Calculate the power loss in a kilometer of such wire... Problem 59PE: Integrated Concepts Cold vaporizers pass a current through water, evaporating it with only a small... Problem 60PE: Integrated Concepts (a) What energy is dissipated by a lightning bolt having a 20,000-A current, a... Problem 61PE: Integrated Concepts What current must be produced by a 12.0-V battery-operated bottle warmer in... Problem 62PE: Integrated Concepts How much time is needed for a surgical cauterizer to raise the temperature of... Problem 63PE: Integrated Concepts Hydroelectric generators (see Figure 20.43) at Hoover Dam produce a maximum... Problem 64PE: Integrated Concepts (a) Assuming 95.0% efficiency for the conversion of electrical power by the... Problem 65PE: Integrated Concepts A light-rail commuter train draws 630 A of 650-V DC electricity when... Problem 66PE: Integrated Concepts (a) An aluminum power transmission line has a resistance of 0.0580/km. What is... Problem 67PE: Integrated Concepts (a) An immersion heater utilizing 120 V can raise the temperature of a 1.00 102... Problem 68PE: Integrated Concepts (a) What is the cost of heating a hot tub containing 1500 kg of water from... Problem 69PE: Unreasonable Results (a) What current is needed to transmit 1.00 102MW of power at 480 V? (b) What... Problem 70PE: Unreasonable Results (a) What current is needed to transmit 1.00 102 MW of power at 10.0kV? (b)... Problem 71PE: Construct Your Own Problem Consider an electric immersion heater used to heat a cup of water to make... Problem 72PE: (a) What is the hot resistance of a 25-W light bulb that runs on 120-V AC? (b) If the bulb’s... Problem 73PE: Certain heavy industrial equipment uses AC power that has a peak voltage of 679 V. What is the rms... Problem 74PE: A certain circuit breaker trips when the rms current is 15.0 A. What is the corresponding peak... Problem 75PE: Military aircraft use 400-Hz AC power, because it is possible to design lighter-weight equipment at... Problem 76PE: A North American tourist takes his 25.0-W, 120-V AC razor to Europe, finds a special adapter, and... Problem 77PE: In this problem, you will verify statements made at the end of the power losses for Example 20.10.... Problem 78PE: A small office-building air conditioner operates or 408-V AC and consumes 50.0 kW. (a) What is its... Problem 79PE: What is the peak power consumption of a 12G-V AC microwave over that draws 10.0A? Problem 80PE: What is the peak current through a 500-W room heater that operates on 120-V AC power? Problem 81PE: Two different electrical devices have the same power consumption, but one is meant to be operated on... Problem 82PE: Nichrome wire is used in some radiative heaters. (a) Find the resistance needed if the average power... Problem 83PE: Find the time after t = 0 when the instantaneous voltage of 60-Hz AC first reaches the following... Problem 84PE: (a) At what two times in the first period following t = 0 does the instantaneous voltage in 60-Hz AC... Problem 85PE: (a) Haw much power is dissipated in a short circuit of 240-V AC through a resistance of 0.250 ? (b)... Problem 86PE: What voltage is involved in a 1.44-kW short circuit through a 0.100- resistance? Problem 87PE: Find the current through a person and identify the likely effect on her if she touches a 120-V AC... Problem 88PE: While taking a bath, a person touches the metal case of a radio. The path through the person to the... Problem 89PE: Foolishly trying to fish a burning piece of bread from a toaster with a metal butter knife, a man... Problem 90PE: (a) During surgery, a current as small as 20.0 ? applied directly to the heart may cause ventricular... Problem 91PE: (a) What is the resistance of a 220-V AC short circuit that generates a peak power of 96.8 kW? (b)... Problem 92PE: A heart defibrillator passes 10.0 A through a patient’s torso for 5.00 ms in an attempt to restore... Problem 93PE: Integrated Concepts A short circuit in a 120-V appliance cord has a 0.500- resistance. Calculate the... Problem 94PE: Construct Your Own Problem Consider a person working in an environment where electric currents might... Problem 95PE: Integrated Concepts Use the ECG in Figure 20.34 to determine the heart rate in beats per minute... Problem 96PE: Integrated Concepts (a) Referring to Figure 20.34, find the time systolic pressure lags behind the... Problem 17PE: SPEAR, a storage ring about 72.0 m in diameter at the Stanford Linear Accelerator (closed in 2009),...
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Concept explainers
SPEAR, a storage ring about 72.0 m in diameter at the Stanford Linear Accelerator (closed in 2009), has a 20.0-A circulating beam of electrons that are moving at nearly the speed of light . How many electrons are in the beam?
Transcribed Image Text: 72 m
L=-20 A.
Area A
Figure 20.39 Electrons circulating in the storage ring called SPEAR
constitute a 20.0-A current. Because they travel close to the speed of
light, each electron completes many orbits in each second.
Definition Definition Rate at which light travels, measured in a vacuum. The speed of light is a universal physical constant used in many areas of physics, most commonly denoted by the letter c . The value of the speed of light c = 299,792,458 m/s, but for most of the calculations, the value of the speed of light is approximated as c = 3 x 10 8 m/s.
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