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... format_list_bulleted
