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…

College Physics

1st Edition

ISBN:9781938168000

Author:Paul Peter Urone, Roger Hinrichs

Publisher:Paul Peter Urone, Roger Hinrichs

Chapter20: Electric Current, Resistance, And Ohm's Law

Section: Chapter Questions

Problem 37PE: (a) Digital medical thermometers determine temperature by measuring the resistance of a...

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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.
Which of the following statements about resistance for a length of conductor is NOT correct? a. The larger the cross section area, the lower the resistance of the conductor. b. The larger the cross-section area, the higher the resistance of the conductor. c. The longer the conductor, the higher the resistance of the conductor. d. The lower the resistivity of the material, the lower the resistance of the conductor.
Question Completion Status: QUESTION 1 What happens to the amount of current running through a circuit if you increase the RESISTANCE of the circuit? Oa. decreases Ob. none of these OC. no change Od.jncreases QUESTION 2 You are looking at two batteries, the first has a voltage of 1.5 volts while the second has a voltage of 24 volts. Which battery will supply a greater current flow when connected to a 4 ohm resistor? a. O volt battery Ob. 24 volt battery Oc. 1.5 volt battery Od. None of these QUESTION 3 What is the current travelling through a 25.5 ohm resistor if there is a 9 volt battery connected to it? a. 0.343 amps b.2.833 amps OC. 4 amps d. 230 amps Click Save and Submit to save and submit. Click Save All Answers to save all answers.
James states that the resistance of a copper wire can be increased making it narrower and longer. Andrew disagrees and argues that resistance can be increased by heating the wire. Which one, if either, is correct, and why? a. James, because the conductivity of a copper wire does not increase when it is hammered. b. Andrew, because the conductivity of the wire decreases when it is heated. c. None of these options d. Andrew, because the conductivity of the wire increases when it is heated. e. Both are correct because the conductivity of a conductor is independent of its shape but decreases with increase in temperature. f. James, because the conductivity of a wire is directly proportional to its area and inversely proportional to its length.
A person gains weight by adding fat—and therefore adding girth—to his body and his limbs, with the amount of muscle remaining constant. How will this affect the electrical resistance of his limbs?A. The resistance will increase.B. The resistance will stay the same.C. The resistance will decrease.
10. A resistor made from a material with a p = 78 Ω m. The resistor is cylindrical with a length of 3.9 cm and a radius of 0.22 cm. A) What is the resistance of the resistor? B) What will the current through the resistor be if it is connected to a 3 V battery? C) How much charge passes through the resistor after 20 seconds?

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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.