PHYSICS F/SCI.+ENGINEERS-ACCESS
PHYSICS F/SCI.+ENGINEERS-ACCESS
4th Edition
ISBN: 9780131992269
Author: GIANCOLI
Publisher: PEARSON
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Textbook Question
Chapter 26, Problem 1Q

Explain why birds can sit on power lines safely, whereas leaning a metal ladder up against a power line to fetch a stuck kite is extremely dangerous.

Expert Solution & Answer
Check Mark
To determine

The reason why it is safe for the birds to sit on the power lines, but leaning a metal ladder against a power line is extremely dangerous.

Answer to Problem 1Q

The resistance of the bird is larger compared to the resistance of the wire between the bird’s feet, so that a very little current passes through the bird as it sits on the power line.

A metal ladder leaned against a power line will have a direct contact between the high potential line and ground which implies person standing on the ladder will have a larger potential difference between his hand and feet which produces large current through the person’s body large enough to cause substantial damage.

Explanation of Solution

Even though the bird’s feet are at high potential compared to the ground, the potential difference between the feet of the bird is very little since they are close together on the wire. And also the resistance of the bird is much greater when compared to the resistance of the wire between the bird’s feet. These two resistance are in parallel so that only a very little current will pass through the bird when it sits on the transmission line.

A metal ladder leaned against a power line will have a direct contact to the high potential line and ground so that the person standing on the ladder will have a larger potential difference between his hand and feet.

Even if the person’s resistance is large, the potential difference will also be so large to produce current through the person’s body large enough to cause severe damage or death.

Therefore, it is safe for the birds to sit on the power lines, but leaning a metal ladder against a power line is extremely dangerous.

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02:07

Chapter 26 Solutions

PHYSICS F/SCI.+ENGINEERS-ACCESS

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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