Concept explainers
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.
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.
Want to see more full solutions like this?
Chapter 26 Solutions
PHYSICS F/SCI.+ENGR.,CHAPTERS 1-37
Additional Science Textbook Solutions
Chemistry: A Molecular Approach (4th Edition)
Physics for Scientists and Engineers: A Strategic Approach, Vol. 1 (Chs 1-21) (4th Edition)
Introductory Chemistry (6th Edition)
Microbiology: An Introduction
College Physics: A Strategic Approach (3rd Edition)
Microbiology with Diseases by Body System (5th Edition)
- When a Leyden jar is charged by a hand generator (Fig. 27.1, page 828), the work done by the person turning the crank is stored as electric potential energy in the jar. When a capacitor is charged by a battery, where does the electric potential energy come from?arrow_forwardWhat does it mean when a force is negative? What does it mean when the potential energy is negative?arrow_forwardThe immediate cause of many deaths is ventricular fibrillation, an uncoordinated quivering of the heart, as opposed to proper beating. An electric shock to the chest can cause momentary paralysis of the heart muscle, after which the heart will sometimes start organized beating again. A defibrillator is a device that applies a strong electric shock to the chest over a time of a few milliseconds. The device contains a capacitor of a few microfarads, charged to several thousand volts. Electrodes called paddles, about 8 cm across and coated with conducting paste, are held against the chest on both sides of the heart. Their handles are insulated to prevent injury to the operator, who calls Clear! and pushes a button on one paddle to discharge the capacitor through the patient's chest Assume an energy of 3.00 102 W s is to be delivered from a 30.0-F capacitor. To what potential difference must it be charged?arrow_forward
- Verify the energy unit equivalence that 1 kWh = 3.60106 J.arrow_forwardAccording to its design specification, the timer circuit delaying the closing of an elevator door is to have a capacitance of 32.0 F between two points A and B. When one circuit is being constructed, the inexpensive but durable capacitor installed between these two points is found to have capacitance 34.8 F. To meet the specification, one additional capacitor can be placed between the two points. (a) Should it be in series or in parallel with the 34.8-F capacitor? (b) What should be its capacitance? (c) What If? The next circuit comes down the assembly line with capacitance 29.8 F between A and B. To meet the specification, what additional capacitor should be installed in series or in parallel in that circuit?arrow_forwardAccording to UE=12C(V)2 (Eq. 27.3), a greater capacitance means more energy is stored by the capacitor, but according to UE = Q2/2C (Eq. 27.2), a greater capacitance means less energy is stored. How can both of these equations be correct?arrow_forward
- What determines the severity of a shock? Can you say that a certain voltage is hazardous without further information?arrow_forwardWhy is it possible for a bird to sit on a high-voltage wire without being electrocuted?arrow_forwardYour car was hit by a high voltage DC power line, putting its entire metal body at a potential of 10 kV in relation to the ground. For your own safety, should you exit your car? Explain your response.arrow_forward
- The people who live in suburbs use simultaneously: 2Hp aircon for 3 hrs. 900 watts toaster for 9 mins., a 1.50kW heater for 8 hrs., a 3.4kW broiler for 20 mins. a four 100 watts lamps for 5 hrs. If the total cost she has to pay is $2.50, What is the unit cost per Kw-hr?arrow_forward27). You have a hybrid (m= 1600 kg) car charging its batteries while it is going downhill. It decends over a height of 1500 m. If all this energy (E = 1.0) could be stored in the battery, how much would there be? If you used this energy to get the car going again, how fast would it go? 28). A hydraulic jack has a car (m= 12,000 kg) on one pad of it (A=2.7 m). If the other pad has an area of 40 cm', how much force on that pad is required to lift the car? If you want to lift the car 2m, how far must the other pad be pushed in? 29). You have a constant acceleration drive on your spaceship (m= 10 kg) so that a=0.5 m/s' while at an angle of 15°. The Sun has a constant force on you (called the Solar Wind) that hits you with a force of 10 N. What is the final acceleration on your ship (including direction)? If you start from rest, how fast are you going after 1 year?arrow_forward1. Figure shows the power consumption of a certain household in 1 day. Calculate: (a) the total energy consumed in kWh, (b) the average power per hour over the total 24 hour period. 1200 W PA 800 W 200 W →t (h) 12 2 4 6 8 10 12 2 4 6 8 10 12 noonarrow_forward
- College PhysicsPhysicsISBN:9781938168000Author:Paul Peter Urone, Roger HinrichsPublisher:OpenStax CollegePhysics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage LearningGlencoe Physics: Principles and Problems, Student...PhysicsISBN:9780078807213Author:Paul W. ZitzewitzPublisher:Glencoe/McGraw-Hill
- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and Engineers, Technology ...PhysicsISBN:9781305116399Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningCollege PhysicsPhysicsISBN:9781305952300Author:Raymond A. Serway, Chris VuillePublisher:Cengage Learning