Electrical appliances are connected in series because appliances have different current ratings * true false Kirchhoff's laws are useful in determining the pressure generated in a circuit * True False When the number of resistance are connected in series, the total resistance is none of the mentioned answers Greater than the largest resistance less than the smallest resistance between the smallest and the greatest

Electrical appliances are connected in series because appliances have different current ratings * true false Kirchhoff's laws are useful in determining the pressure generated in a circuit * True False When the number of resistance are connected in series, the total resistance is none of the mentioned answers Greater than the largest resistance less than the smallest resistance between the smallest and the greatest

College Physics

11th Edition

ISBN:9781305952300

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter17: Current And Resistance

Section: Chapter Questions

Problem 2CQ: A 12-V battery is connected across a device with variable resistance. As the resistance of the...

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Using an ohmmeter, a student measures the resistance between various points on his body. He finds that the resistance between two points on the same finger is about the same as the resistance between two points on opposite hands-both are several hundred thousand ohms. Furthermore, the resistance decreases when more skin is brought into contact with the probes of the ohmmeter. Finally, there is a dramatic drop in resistance (to a few thousand ohms) when the skin is wet. Explain these observations and their implications regarding skin and internal resistance of the human body.
Use the atomic theory of matter to explain why the resistance of a material should increase as its temperature increases.
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
Consider the circuit shown in Figure P18.10. (a) Calculate the equivalent resistance of the 10.0- and 5.00- resistors connected in parallel. (b) Using the result of part (a), calculate the combined resistance of the 10.0-, 5.00-, and 4.00- resistors. (c) Calculate the equivalent resistance of the combined resistance found in part (b) and the parallel 3.00- resistor. (d) Combine the equivalent resistance found in part (c) with the 2.00- resistor. (e) Calculate the total current in the circuit. (f) What is the voltage drop across the 2.00- resistor? (g) Subtracting the result of part (f) from the battery voltage, find the voltage across the 3.00- resistor. (h) Calculate the current in the 3.00- resistor. Figure P18.10
The following statements are related to household circuits and electrical safety. Determine whether each statement is true (T) or false (F). (a) Circuit breakers are wired in series with the outlets they protect. (b) A circuit breaker rated at 20 A provides a constant current of 20 A to each outlet in the circuit. (c) Three-wire electrical cords help prevent dangerous electrical shocks by grounding the case of a device.
A child’s electronic toy is supplied by three 1.58-V alkaline cells having internal resistances of 0.0200 in series with a 1.53-V carbon-zinc dry cell having a 0.100- internal resistance. The load resistance is 10.0 . (a) Draw a circuit diagram of the toy and its batteries, (b) What current flows? (c) How much power is supplied to the load? (d) What is the internal resistance of the dry cell if it goes bad, resulting in only 0.500 W being supplied to the load?
A physics student uses a 115.00-V immersion heater to heat 400.00 grams (almost two cups) of water for herbal tea. During the two minutes it takes the water to heat, the physics student becomes bored and decides to figure our the resistance of the heater. The student starts with the assumption that the water is initially at the temperature of the room Ti=25.00C and reaches Tf=100.00C . The specific heat of the water is c=4180JkgK What is the resistance of the heater?
Consider the circuit shown in Figure P18.11. Find (a) the potential difference between points a and b and (b) the current in the 20.0- resistor. Figure P18.11
Review. A well-insulated electric water heater warms 109 kg of water from 20.0C to 49.0C in 25.0 min. Find the resistance of its heating element, which is connected across a 240-V potential difference.
The circuit shown in Figure P27.17 is connected for 2.00 min. (a) Determine the current in each branch of the circuit. (b) Find the energy delivered by each battery. (c) Find the energy delivered to each resistor. (d) Identify the type of energy storage transformation that occurs in the operation of the circuit. (e) Find the total amount of energy transformed into internal energy in the resistors.
A child's electronic toy is supplied by three 1.58-V alkaline cells having internal resistances of 0.0200 inseries with a 1.53-V carbon-zinc dry cell having a 0.100- internal resistance. The load resistance is 10.0 . (a) Draw a circuit diagram of the toy and itsbatteries, (b) What current flows? (c) How much power is supplied to the load? (d) What is the internal resistance of the dry cell if it goes bad, resulting in only 0.500 W being supplied to the load?
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.