Physics for Scientists and Engineers with Modern Physics
4th Edition
ISBN: 9780131495081
Author: Douglas C. Giancoli
Publisher: Addison-Wesley
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Textbook Question
Chapter 26, Problem 84GP
Some light-dimmer switches use a variable resistor as shown in Fig. 26–73. The slide moves from position x = 0 to x = 1, and the resistance up to slide position x is proportional to x (the total resistance is Rvar = 150 Ω at x = 1). What is the power expended in the lightbulb if (a) x = 1.00, (b) x = 0.65, (c) x = 0.35?
FIGURE 26–73 Problem 84.
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Chapter 26 Solutions
Physics for Scientists and Engineers with Modern Physics
Ch. 26.1 - Repeat Example 261 assuming now that the...Ch. 26.2 - You have a 10- and a 15- resistor. What is the...Ch. 26.3 - Write the equation for the lower loop abcdefga of...Ch. 26.4 - If the jumper cables of Example 2610 were...Ch. 26.5 - In 10 times constants, the charge on the capacitor...Ch. 26 - Explain why birds can sit on power lines safely,...Ch. 26 - Discuss the advantages and disadvantages of...Ch. 26 - If all you have is a 120-V line, would it be...Ch. 26 - Two lightbulbs of resistance R1 and R2 (R2 R1)...Ch. 26 - Household outlets are often double outlets. Are...
Ch. 26 - With two identical lightbulbs and two identical...Ch. 26 - If two identical resistors are connected in series...Ch. 26 - You have a single 60-W bulb on in your room. How...Ch. 26 - When applying Kirchhoffs loop rule (such as in...Ch. 26 - Compare and discuss the formulas for resistors and...Ch. 26 - For what use are batteries connected in series?...Ch. 26 - Can the terminal voltage of a battery ever exceed...Ch. 26 - Explain in detail how you could measure the...Ch. 26 - In an RC circuit, current flows from the battery...Ch. 26 - Given the circuit shown in Fig. 2634, use the...Ch. 26 - Figure 2635 is a diagram of a capacitor (or...Ch. 26 - Design a circuit in which two different switches...Ch. 26 - What is the main difference between an analog...Ch. 26 - What would happen if you mistakenly used an...Ch. 26 - Explain why an ideal ammeter would have zero...Ch. 26 - A voltmeter connected across a resistor always...Ch. 26 - A small battery-operated flashlight requires a...Ch. 26 - Different lamps might have batteries connected in...Ch. 26 - Prob. 1PCh. 26 - (I) Four 1.50-V cells are connected in series to a...Ch. 26 - (II) A 1.5-V dry cell can be tested by connecting...Ch. 26 - (II) What is the internal resistance of a 12.0-V...Ch. 26 - (I) A 650- and a 2200- resistor are connected in...Ch. 26 - (I) Three 45- lightbulbs and three 65- lightbulbs...Ch. 26 - (I) Suppose that you have a 680-, a 720-, and a...Ch. 26 - (I) How many 10- resistors must be connected in...Ch. 26 - (II) Suppose that you have a 9.0-V battery and you...Ch. 26 - Three 1.70-k resistors can be connected together...Ch. 26 - (II) A battery with an emf of 12.0 V shows a...Ch. 26 - (II) Eight identical bulbs are connected in series...Ch. 26 - (II) Eight bulbs are connected in parallel to a...Ch. 26 - (II) The performance of the starter circuit in an...Ch. 26 - (II) A close inspection of an electric circuit...Ch. 26 - (II) Determine (a) the equivalent resistance of...Ch. 26 - (II) A 75-W, 110-V bulb is connected in parallel...Ch. 26 - (II) (a) Determine the equivalent resistance of...Ch. 26 - (II) Whal is the net resistance of the circuit...Ch. 26 - (II) Calculate the current through each resistor...Ch. 26 - (II) The two terminals of a voltage source with...Ch. 26 - (II) Two resistors when connected in series to a...Ch. 26 - (III) Three equal resistors (R) are connected to a...Ch. 26 - (III) A 2.8-k and a 3.7-k resistor are connected...Ch. 26 - (III) Consider the network of resistors shown in...Ch. 26 - (III) You are designing a wire resistance heater...Ch. 26 - (I) Calculate the current in the circuit of Fig....Ch. 26 - (II) Determine the terminal voltage of each...Ch. 26 - (II) For the circuit shown in Fig. 2647, find the...Ch. 26 - (II) (a) A network of five equal resistors R is...Ch. 26 - (II) (a) What is the potential difference between...Ch. 26 - (II) Calculate the currents in each resistor of...Ch. 26 - (II) Determine the magnitudes and directions of...Ch. 26 - (II) Determine the magnitudes and directions of...Ch. 26 - (II) A voltage V is applied to n identical...Ch. 26 - (III) (a) Determine the currents I1, I2, and I3 in...Ch. 26 - (III) What would the current I1 be in Fig. 2653 if...Ch. 26 - (III) Determine the current through each of the...Ch. 26 - (III) If the 25- resistor in Fig. 2654 is shorted...Ch. 26 - (III) Twelve resistors, each of resistance R, are...Ch. 26 - (III) Determine the net resistance in Fig. 2656...Ch. 26 - (II) Suppose two batteries, with unequal emfs of...Ch. 26 - (I) Estimate the range of resistance needed to...Ch. 26 - (II) In Fig. 2658 (same as Fig. 2617a), the total...Ch. 26 - (II) Two 3.8-F capacitors, two 2.2-k resistors,...Ch. 26 - (II) How long does it take for the energy stored...Ch. 26 - (II) A parallel-plate capacitor is filled with a...Ch. 26 - (II) The RC circuit of Fig. 2659 (same as Fig....Ch. 26 - (II) Consider the circuit shown in Fig. 2660,...Ch. 26 - (III) Determine the time constant for charging the...Ch. 26 - (III) Two resistors and two uncharged capacitors...Ch. 26 - (III) Suppose the switch S in Fig. 2662 is closed....Ch. 26 - (I) An ammeter has a sensitivity of 35,00 /V. What...Ch. 26 - (I) What is the resistance of a voltmeter on the...Ch. 26 - (II) A galvanometer has a sensitivity of 45 k/V...Ch. 26 - (II) A galvanometer has an internal resistance of...Ch. 26 - (II) A particular digital meter is based on an...Ch. 26 - (II) A milliammeter reads 25 mA full scale. It...Ch. 26 - (II) A 45-V battery of negligible internal...Ch. 26 - (II) An ammeter whose internal resistance is 53 ...Ch. 26 - (II) A battery with E=12.0V and internal...Ch. 26 - (II) A 12.0-V battery (assume the internal...Ch. 26 - (III) Two 9.4-k resistors are placed in series and...Ch. 26 - (III) When the resistor R in Fig. 2664 is 35 , the...Ch. 26 - Suppose that you wish to apply a 0.25-V potential...Ch. 26 - A three-way lightbulb can produce 50 W, 100 W, or...Ch. 26 - Suppose you want to run some apparatus that is 65...Ch. 26 - For the circuit shown in Fig. 2618a, show that the...Ch. 26 - A heart pacemaker is designed to operate at 72...Ch. 26 - Prob. 70GPCh. 26 - A Wheatstone bridge is a type of bridge circuit...Ch. 26 - An unknown length of platinum wire 1.22 mm in...Ch. 26 - The internal resistance of a 1.35-V mercury cell...Ch. 26 - How many 12-W resistors, each of the same...Ch. 26 - A solar cell, 3.0 cm square, has an output of 350...Ch. 26 - A power supply has a fixed output voltage of 12.0...Ch. 26 - The current through the 4.0-k resistor in Fig....Ch. 26 - A battery produces 40.8 V when 7.40 A is drawn...Ch. 26 - In the circuit shown in Fig. 2668, the 33-...Ch. 26 - The current through the 20- resistor in Fig. 2669...Ch. 26 - (a) A voltmeter and an ammeter can be connected as...Ch. 26 - (a) What is the equivalent resistance of the...Ch. 26 - A flashlight bulb rated at 2.0 W and 3.0 V is...Ch. 26 - Some light-dimmer switches use a variable resistor...Ch. 26 - A potentiometer is a device to precisely measure...Ch. 26 - Electronic devices often use an RC circuit to...Ch. 26 - The circuit shown in Fig. 2676 is a primitive...Ch. 26 - Determine the current in each resistor of the...Ch. 26 - In the circuit shown in Fig. 2678, switch S is...Ch. 26 - Figure 2679 shows the circuit for a simple...Ch. 26 - Measurements made on circuits that contain large...Ch. 26 - A typical voltmeter has an internal resistance of...Ch. 26 - (II) An RC series circuit contains a resistor R =...
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