Physics (5th Edition)
5th Edition
ISBN: 9780321976444
Author: James S. Walker
Publisher: PEARSON
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Textbook Question
Chapter 21, Problem 30PCE
Predict/Calculate A 65-W lightbulb operates on a potential difference of 95 V. Find (a) the current in the bulb and (b) the resistance of the bulb. (c) If this bulb is replaced with one whose resistance is half the value found in part (b), is its power rating greater than or less than 65 W? By what factor?
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Chapter 21 Solutions
Physics (5th Edition)
Ch. 21.1 - Enhance Your Understanding 1. The following...Ch. 21.2 - Enhance Your Understanding 2. If the voltage and...Ch. 21.3 - Enhance Your Understanding 3. In the following...Ch. 21.4 - The two circuits shown in Figure 21-17 have...Ch. 21.5 - Prob. 5EYUCh. 21.6 - Do two capacitors give a larger equivalent...Ch. 21.7 - Give a symbolic expression for the current that...Ch. 21 - Your body is composed of electric charges. Does it...Ch. 21 - Suppose you charge a comb by rubbing it through...Ch. 21 - An electron moving through a wire has an average...
Ch. 21 - Are car headlights connected in series or...Ch. 21 - Is it possible to connect a group of resistors of...Ch. 21 - What physical quantity do resistors connected in...Ch. 21 - What physical quantity do resistors connected in...Ch. 21 - Explain how electrical devices can begin operating...Ch. 21 - Explain the difference between resistivity and...Ch. 21 - Explain why birds can roost on high-voltage wires...Ch. 21 - Consider the circuit shown in Figure 21-36, in...Ch. 21 - A flashlight bulb carries a current of 0.38 A for...Ch. 21 - Predict/Calculate A car battery does 360 J of work...Ch. 21 - Highly sensitive ammeters can measure currents as...Ch. 21 - A television set connected to a 120-V outlet...Ch. 21 - BIO Pacemaker Batteries Pacemakers designed for...Ch. 21 - A conducting wire is quadrupled in length and...Ch. 21 - Figure 21-37 shows a plot of current versus...Ch. 21 - Predict/Explain Current-versus-voltage plots for...Ch. 21 - Prob. 9PCECh. 21 - When a potential difference of 12 V is applied to...Ch. 21 - Prob. 11PCECh. 21 - Prob. 12PCECh. 21 - Transcranial Direct-Current Stimulation In a tDCS...Ch. 21 - The four conducting cylinders shown in Figure...Ch. 21 - Predict/Calculate A bird lands on a bare copper...Ch. 21 - Prob. 16PCECh. 21 - Predict/Calculate BIO Current Through a Cell...Ch. 21 - Prob. 18PCECh. 21 - Prob. 19PCECh. 21 - BIO Resistance and Current in the Human Finger The...Ch. 21 - If a potential difference V is maintained between...Ch. 21 - Light A has four times the power rating of light B...Ch. 21 - Two lightbulbs operate on the same potential...Ch. 21 - Problems and Conceptual Exercises Section 21-3...Ch. 21 - A 65-V generator supplies 4.8 kW of power. How...Ch. 21 - A portable CD player operates with a current of 18...Ch. 21 - Find the power dissipated in a 22- electric heater...Ch. 21 - The current in a 120-V reading lamp is 2.6 A. If...Ch. 21 - Circuit A in a house has a voltage of 208 V and is...Ch. 21 - Predict/Calculate A 65-W lightbulb operates on a...Ch. 21 - Rating Car Batteries Car batteries are rated by...Ch. 21 - Predict/Explain A dozen identical lightbulbs are...Ch. 21 - A circuit consists of three resistors, R1 R2 R3,...Ch. 21 - Predict/Explain Two resistors are connected in...Ch. 21 - What is the minimum number of 88- resistors that...Ch. 21 - Find the equivalent resistance between points A...Ch. 21 - A 9.00-V battery is connected across the terminals...Ch. 21 - Holiday Lights In a string of holiday lights, 50...Ch. 21 - Your toaster has a power cord with a resistance of...Ch. 21 - Prob. 40PCECh. 21 - Predict/Calculate Three resistors, 11, 53 , and R,...Ch. 21 - A circuit consists of a battery connected to three...Ch. 21 - Predict/Calculate Three resistors, 22 , 67 , and...Ch. 21 - Prob. 44PCECh. 21 - The equivalent resistance between points A and B...Ch. 21 - Find the equivalent resistance between points A...Ch. 21 - How many 23-W lightbulbs can be connected in...Ch. 21 - The circuit in Figure 21-43 includes a battery...Ch. 21 - Predict/Calculate A 12-V battery is connected to...Ch. 21 - Predict/Calculate The terminals A and B in Figure...Ch. 21 - Predict/Calculate Suppose the battery in Figure...Ch. 21 - Predict/Calculate The current flowing through the...Ch. 21 - Predict/Calculate Four identical resistors are...Ch. 21 - Find the magnitude and direction (clockwise or...Ch. 21 - Predict/Calculate Suppose the polarity of the...Ch. 21 - Predict/Calculate It is given that point A in...Ch. 21 - Consider the circuit shown in Figure 21-47. Find...Ch. 21 - Suppose point A is grounded (V = 0) in Figure...Ch. 21 - Predict/Calculate (a) Find the current in each...Ch. 21 - Two batteries and three resistors are connected as...Ch. 21 - Two capacitors, C1 = C and C2 = 2C, are connected...Ch. 21 - Predict/Explain Two capacitors are connected in...Ch. 21 - Predict/Explain Two capacitors are connected in...Ch. 21 - A 252-F capacitor is connected in series with a...Ch. 21 - A 36-F capacitor is connected in parallel with an...Ch. 21 - Find the equivalent capacitance between points A...Ch. 21 - A 15-V battery is connected to three capacitors in...Ch. 21 - Three different circuits, each containing a switch...Ch. 21 - Terminals A and B in Figure 21-50 are connected to...Ch. 21 - Predict/Calculate You would like to add a second...Ch. 21 - Two capacitors, one 7.5 F and the other 15 F, are...Ch. 21 - The equivalent capacitance of the capacitors shown...Ch. 21 - With the switch in position A, the 11.2-F...Ch. 21 - The switch on an RC circuit is closed at t = 0....Ch. 21 - The capacitor in an RC circuit (R = 120 , C = 45...Ch. 21 - Three RC circuits have the emf, resistance, and...Ch. 21 - Consider an RC circuit with = 12.0 V, R = 195 ,...Ch. 21 - The resistor in an RC circuit has a resistance of...Ch. 21 - A flash unit for a camera has a capacitance of...Ch. 21 - Figure 21-54 shows a simplified circuit for a...Ch. 21 - Nerve Impulse Propagation The speed with which...Ch. 21 - Predict/Calculate Consider the RC circuit shown in...Ch. 21 - CE Consider the circuit shown in Figure 21-56, in...Ch. 21 - CE Predict/Explain (a) Referring to Problem 83 and...Ch. 21 - CE Consider the circuit shown in Figure 21-57, in...Ch. 21 - CE Predict/Explain (a) When the switch is closed...Ch. 21 - Suppose that points A and B in Figure 21-41 are...Ch. 21 - CE The circuit shown in Figure 21-58 shows a...Ch. 21 - CE The three circuits shown in Figure 21-59 have...Ch. 21 - Electrical Safety Codes For safety reasons,...Ch. 21 - A portable CD player uses a current of 7.5 mA at a...Ch. 21 - An electrical heating coil is immersed in 6.6 kg...Ch. 21 - Predict/Calculate Consider the circuit shown in...Ch. 21 - Prob. 94GPCh. 21 - BIO Pacemaker Pulses A pacemaker sends a pulse to...Ch. 21 - Three resistors (R,12R,2R) are connected to a...Ch. 21 - Predict/Calculate Suppose we connect a 12.0-V...Ch. 21 - National Electric Code In the United States, the...Ch. 21 - Solar Panel Power The current-versus-voltage plot...Ch. 21 - Predict/Calculate A 15.0-V battery is connected to...Ch. 21 - When two resistors, R1 and R2, are connected in...Ch. 21 - The circuit shown in Figure 21-62 is known as a...Ch. 21 - BIO Footwear Safety The American National...Ch. 21 - BIO Footwear Safety The American National...Ch. 21 - BIO Footwear Safety The American National...Ch. 21 - The standard specifies that footwear should be...Ch. 21 - Referring to Example 21-13 Suppose the three...Ch. 21 - Referring to Example 21-13 Suppose R1 = R2 = 225 ...Ch. 21 - Predict/Calculate Referring to Example 21-18...Ch. 21 - Predict/Calculate Referring to Example 21-18...
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