College Physics
OER 2016 Edition
ISBN: 9781947172173
Author: OpenStax
Publisher: OpenStax College
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Textbook Question
Chapter 20, Problem 71PE
Construct Your Own Problem
Consider an electric immersion heater used to heat a cup of water to make tea. Construct a problem in which you calculate the needed resistance of the heater so that it increases the temperature of the water and cup in a reasonable amount of time. Also calculate the cost of the electrical energy used in your process. Among the things to be considered are the voltage used, the masses and heat capacities involved, heat losses, and the time over which the heating takes place. Your instructor may wish for you to consider a thermal safety switch (perhaps bimetallic) that will halt the process before damaging temperatures are reached in the immersion unit.
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1) A resistor has a value of 20 ohms (Ω) when it is at 15 degrees Celsius. If the coefficient of thermal resistivity is 3.5 x 10-3/ Celsius, determine the value of the resistance at 97 degrees Celsius. Write your result to 3 significant figures.
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Chapter 20 Solutions
College Physics
Ch. 20 - Can a wire carry a current and still be...Ch. 20 - Car batteries are rated in ampere-hours (A h )....Ch. 20 - If two different wires having identical...Ch. 20 - Why are two conducting paths from a voltage source...Ch. 20 - In cars, one battery terminal is connected to the...Ch. 20 - Why isn't a bird sitting on a high-voltage power...Ch. 20 - The IR drop across a resistor means that there is...Ch. 20 - How is the I R drop in a resistor similar to the...Ch. 20 - In which of the three semiconducting materials...Ch. 20 - Prob. 10CQ
Ch. 20 - If aluminum and copper wires of the same length...Ch. 20 - Explain why R=R0(1 + a?T) for the temperature...Ch. 20 - Why do incandescent lightbulbs grow dim late in...Ch. 20 - The power dissipated in a resistor is given by P =...Ch. 20 - Give an example of a use of AC power other than in...Ch. 20 - Why do voltage, current, and power go through zero...Ch. 20 - You are riding in a train, gazing into the...Ch. 20 - Using an ohmmeter, a student measures the...Ch. 20 - What are the two major hazards of electricity?Ch. 20 - Why isn’t a short circuit a shock hazard?Ch. 20 - What determines the severity of a shock? Can you...Ch. 20 - An electrified needle is used to burn off warts,...Ch. 20 - Some surgery is performed with high-voltage...Ch. 20 - Some devices often used in bathrooms, such as...Ch. 20 - We are often advised to not flick electric...Ch. 20 - Before working on a power transmission line,...Ch. 20 - Why is the resistance of wet skin so much smaller...Ch. 20 - Could a person on intravenous infusion (an IV) be...Ch. 20 - In view of the small currents that cause shock...Ch. 20 - Prob. 30CQCh. 20 - Define depolarization, repolarization, and the...Ch. 20 - Explain the properties of myelinated nerves in...Ch. 20 - What is the current in milliamperes produced by...Ch. 20 - A total of 600 C of charge passes through a...Ch. 20 - What is the current when a typical static charge...Ch. 20 - Find the current when 2.00 nC jumps between your...Ch. 20 - A large lightning bolt had a 20,000-A current and...Ch. 20 - The 200-A current through a spark plug moves 0.300...Ch. 20 - Prob. 7PECh. 20 - During open-heart surgery, a defibrillator can be...Ch. 20 - (a) A defibrillator passes 12.0 A of current...Ch. 20 - A clock battery wears out after moving 10,000 C of...Ch. 20 - The batteries of a submerged non-nuclear submarine...Ch. 20 - Electron guns are used in X-ray tubes. The...Ch. 20 - A large cyclotron directs a beam of He ++ nuclei...Ch. 20 - Repeat the above example on Example 20.3, but for...Ch. 20 - Using the results of the above example on Example...Ch. 20 - A 14-gauge copper wire has a diameter of 1.628 mm....Ch. 20 - Prob. 17PECh. 20 - What current flows through the bulb of a 3.00-V...Ch. 20 - Calculate the effective resistance of a pocket...Ch. 20 - What is the effective resistance of a car’s...Ch. 20 - How many volts are supplied to operate an...Ch. 20 - (a) F ind the voltage drop in an extension cord...Ch. 20 - A power transmission line is hung from metal...Ch. 20 - What is the resistance of a 20.0-m-long piece of...Ch. 20 - The diameter of 0-gauge copper wire is 8.252 mm....Ch. 20 - If the 0.100-mm diameter tungsten filament in a...Ch. 20 - Find the ratio of the diameter of aluminum to...Ch. 20 - What current flows through a 2.54-cm-diameter rod...Ch. 20 - (a) To what temperature must you raise a copper...Ch. 20 - A resistor made of Nichrome wire is used in an...Ch. 20 - Of what material is a resistor made if its...Ch. 20 - An electronic device designed to operate at any...Ch. 20 - a) Of what material is a wire made, if it is 25.0...Ch. 20 - Assuming a constant temperature coefficient of...Ch. 20 - A wire is drawn through a die, stretching it to...Ch. 20 - A copper wire has a resistance of 0.500at 20.0°C,...Ch. 20 - (a) Digital medical thermometers determine...Ch. 20 - Integrated Concepts (a) Redo Exercise 20.25 taking...Ch. 20 - Unreasonable Results (a) To what temperature must...Ch. 20 - What is the power of a 1.00 102 MV lightning boit...Ch. 20 - What power is supplied to the starter motor of a...Ch. 20 - Prob. 42PECh. 20 - How many watts does a flashlight that has 6.00102C...Ch. 20 - Find the power dissipated in each of these...Ch. 20 - Verify that the units of a volt-ampere are watts,...Ch. 20 - Show that the units 1 V2/=1W , as implied by the...Ch. 20 - Show that the units 1 A 2 = 1W, as implied by the...Ch. 20 - Verify the energy unit equivalence that 1 kWh =...Ch. 20 - Electrons in an X-ray tube are accelerated through...Ch. 20 - Prob. 50PECh. 20 - With a 1200-W toaster, how much electrical energy...Ch. 20 - What would be the maximum cost of a CFL such that...Ch. 20 - Some makes of older cars have 6.00-V electrical...Ch. 20 - Alkaline batteries have the advantage of putting...Ch. 20 - A cauterizer, used to stop bleeding in surgery,...Ch. 20 - The average television is said to be on 6 hours...Ch. 20 - An old lightbulb draws only 50.0 W, rather than...Ch. 20 - -gauge copper wire has a diameter of 9.266 mm....Ch. 20 - Prob. 59PECh. 20 - Integrated Concepts (a) What energy is dissipated...Ch. 20 - Integrated Concepts What current must be produced...Ch. 20 - Integrated Concepts How much time is needed for a...Ch. 20 - Prob. 63PECh. 20 - Prob. 64PECh. 20 - Integrated Concepts A light-rail commuter train...Ch. 20 - Integrated Concepts (a) An aluminum power...Ch. 20 - Integrated Concepts (a) An immersion heater...Ch. 20 - Integrated Concepts (a) What is the cost of...Ch. 20 - Unreasonable Results (a) What current is needed to...Ch. 20 - Unreasonable Results (a) What current is needed to...Ch. 20 - Construct Your Own Problem Consider an electric...Ch. 20 - (a) What is the hot resistance of a 25-W light...Ch. 20 - Certain heavy industrial equipment uses AC power...Ch. 20 - A certain circuit breaker trips when the rms...Ch. 20 - Military aircraft use 400-Hz AC power, because it...Ch. 20 - A North American tourist takes his 25.0-W, 120-V...Ch. 20 - In this problem, you will verify statements made...Ch. 20 - A small office-building air conditioner operates...Ch. 20 - What is the peak power consumption of a 12G-V AC...Ch. 20 - What is the peak current through a 500-W room...Ch. 20 - Two different electrical devices have the same...Ch. 20 - Nichrome wire is used in some radiative heaters....Ch. 20 - Find the time after t = 0 when the instantaneous...Ch. 20 - (a) At what two times in the first period...Ch. 20 - (a) Haw much power is dissipated in a short...Ch. 20 - What voltage is involved in a 1.44-kW short...Ch. 20 - Find the current through a person and identify the...Ch. 20 - While taking a bath, a person touches the metal...Ch. 20 - Foolishly trying to fish a burning piece of bread...Ch. 20 - (a) During surgery, a current as small as 20.0 ?...Ch. 20 - (a) What is the resistance of a 220-V AC short...Ch. 20 - A heart defibrillator passes 10.0 A through a...Ch. 20 - Integrated Concepts A short circuit in a 120-V...Ch. 20 - Construct Your Own Problem Consider a person...Ch. 20 - Prob. 95PECh. 20 - Prob. 96PECh. 20 - Prob. 1TPCh. 20 - Prob. 2TPCh. 20 - Prob. 3TPCh. 20 - Prob. 4TPCh. 20 - Prob. 5TPCh. 20 - Prob. 6TPCh. 20 - Prob. 7TPCh. 20 - Prob. 8TPCh. 20 - Prob. 9TPCh. 20 - Prob. 10TPCh. 20 - Prob. 11TPCh. 20 - Prob. 12TPCh. 20 - Prob. 13TPCh. 20 - Prob. 14TPCh. 20 - Prob. 15TP
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