Book cover for Physics

Physics

John D. Cutnell, Kenneth W. Johnson, David Young, Shane Stadler

ISBN #9781118486894

10th Edition

2,562 Questions

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Summary

Learning Objectives

Key Concepts

Example Problems

Explanations

Common Mistakes

Summary

This textbook section covers the fundamental principles governing electric circuits, including the definitions of electromotive force, electric current, and resistance. It reviews Ohm’s law and the methods to calculate resistance based on material properties, as well as the methods for calculating electric power in both DC and AC circuits. Additionally, it explores complex circuit analysis methods such as series-parallel combinations, Kirchhoff’s rules, and the role of internal resistance. It also introduces capacitors—how they combine in series and parallel—and RC circuits with their characteristic time constants. Lastly, practical considerations such as proper measurement techniques and safety via grounding are discussed.

Learning Objectives

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Key Concepts

CONCEPT

DEFINITION

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Example Problems

Example 1

A defibrillator is used during a heart attack to restore the heart to its normal beating pattern (see Section 19.5 ). A defibrillator passes 18 A of current through the torso of a person in $2.0 \mathrm{ms}$. (a) How much charge moves during this time? (b) How many electrons pass through the wires connected to the patient?

Example 2

An especially violent lightning bolt has an average current of $1.26 \times$ $10^{3}$ A lasting 0.138 s. How much charge is delivered to the ground by the lightning bolt?

Example 3

A battery charger is connected to a dead battery and delivers a current of $6.0 \mathrm{A}$ for 5.0 hours, keeping the voltage across the battery terminals at $12 \mathrm{V}$ in the process. How much energy is delivered to the battery?

Example 4

A coffee-maker contains a heating element that has a resistance of 14 $\Omega .$ This heating element is energized by a $120-\mathrm{V}$ outlet. What is the current in the heating element?

Example 5

Suppose that the resistance between the walls of a biological cell is $5.0 \times 10^{\circ} \Omega .$ (a) What is the current when the potential difference between the walls is $75 \mathrm{mV} ?$ (b) If the current is composed of $\mathrm{Na}^{+}$ ions $(q=+e),$ how many such ions flow in $0.50 \mathrm{s} ?$

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Step-by-Step Explanations

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Common Mistakes

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