3.What quantities determine the resistance of a piece of material? Choose all that apply.A. The cross-sectional area of the piece of materialB. The type of materialC. The current flowing through the piece of materialD. The voltage across the materialE. The length of the piece of material3.

1. The type of material: Different materials have different resistivities, which is a fundamental…

Answered: 3. What quantities determine the…

Principles of Physics: A Calculus-Based Text

5th Edition

ISBN:9781133104261

Author:Raymond A. Serway, John W. Jewett

Publisher:Raymond A. Serway, John W. Jewett

Chapter21: Current And Direct Current Circuits

Section: Chapter Questions

Problem 16P

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(a) Digital medical thermometers determine temperature by measuring the resistance of a semiconductor device called a thermistor (which has a= - 0.0600/°C ) when it is at the same temperature as the patient. What is a patient's temperature if the thermistor’s resistance at that temperature is 82.0% of its value at 37.0°C (normal body temperature)? (b) The negative value for a may not be maintained for very low temperatures. Discuss why and whether this is the case here. (Hint: Resistance can’t become negative.)
(a) A defibrillator sends a 6.00-A current through the chest of a patient by applying a 10,000-V potential as in the figure below. What is the resistance of the path? (b) The defibrillator paddles make contact with the patient through a conducting gel that greatly reduces the path resistance. Discuss the difficulties that would ensue if a larger voltage were used to produce the same current through the patient, but with the path having perhaps 50 times the resistance. (Hint: The current must be about the same, so a higher voltage would imply greater power. Use this equation for power: P=I2 RP = .)
Construct Your Own Problem Consider a person working in an environment where electric currents might pass through her body. Construct a problem in which you calculate the resistance of insulation needed to protect the person from harm. Among the things to be considered are the voltage to which the person might be exposed, likely body resistance (dry, wet, ...), and acceptable currents (safe but sensed, safe and unfelt, ...).
The circuit in Figure P27.34a consists of three resistors and one battery with no internal resistance. (a) Find the current in the 5.00- resistor. (b) Find the power delivered to the 5.00- resistor. (c) In each of the circuits in Figures P27.34b, P27.34c, and P27.34d, an additional 15.0-V battery has been inserted into the circuit. Which diagram or diagrams represent a circuit that requires the use of Kirchhoffs rules to find the currents? Explain why. (d) In which of these three new circuits is the smallest amount of power delivered to the 10.0- resistor? (You need not calculate the power in each circuit if you explain your answer.) Figure P27.34
A person with body resistance between his hands of 1.00 k accidentally grasps the terminals of a 20.0-kV power supply. (Do NOT do this!) (a) Draw a circuit diagram to represent the situation. (b) If the internal resistance of the power supply is 2000 , what is the current through his body? (c) What is the power dissipated in his body? (d) If the power supply is to be made safe by increasing its internal resistance, what should the internal resistance be for the maximum current in this situation to be 1.00 mA or less? (e) Will this modification compromise the effectiveness of the power supply for driving low-re si stance devices? Explain your reasoning,
For the purpose of measuring the electric resistance of shoes through the body of the wearer standing on a metal ground plate, the American National Standards Institute (ANSI) specifies the circuit shown in Figure P27.14. The potential difference V across the 1.00-M resistor is measured with an ideal voltmeter. (a) Show that the resistance of the footwear is Rshoes=50.0VVV (b) In a medical test, a current through the human body should not exceed 150 A. Can the current delivered by the ANSI-specified circuit exceed 150 A? To decide, consider a person standing barefoot on the ground plate. Figure P27.14
-gauge copper wire has a diameter of 9.266 mm. Calculate the power loss in a kilometer of such wire when it carries 1.00102 A.
(a) What is the terminal voltage of a large 1.54-V carbon-zinc dry cell used in a physics lab to supply 2.00 A to a circuit if the cell’s internal resistance is 0.100 ? (b) How much electrical power does the cell produce? (c) What power goes to its load?
When a straight wire is heated, its resistance changes according to the equation R = R0 [1 + (T T0)] (Eq. 17.7), where is the temperature coefficient of resistivity. (a) Show that a more precise result, which includes the length and area of a wire change when it is heated, is R=R0[1+(TT0)][1+(TT0)][1+2(TT0)] where is the coefficient of linear expansion. (See Topic 10.) (b) Compare the two results for a 2.00-m-long copper wire of radius 0.100 mm, starting at 20.0C and heated to 100.0C.
A nichrome rod that is 3.00 mm long with a cross sectional area of 1.00 mm2 is used for a digital thermometer, (a)What is the resistance at room temperature? (b)What is the resistance at body temperature?
Consider the circuits shown below, (a) What is the current through each resistor in part (a)? (b) What is the current through each resistor in part (b)? (c) What is the power dissipated or consumed by each circuit? (d) What is the power supplied to each circuit?
Unreasonable Results (a) To what temperature must you raise a resistor made of constantan to double its resistance, assuming a constant temperature coefficient of resistivity? (b) To cut it in half? (c) What is unreasonable about these results? (d) Which assumptions are unreasonable, or which premises are inconsistent?

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3. What quantities determine the resistance of a piece of material? Choose all that apply. A. The cross-sectional area of the piece of material B. The type of material C. The current flowing through the piece of material D. The voltage across the material E. The length of the piece of material 3.