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Chapter 1

Electric Circuit Variables

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Leyden jar for retaining electrical charges Electrical stimulation to a body

History of Electrical Science

• Amber 의 정전기• Electrical Generator• Battery• Positive & Negative Charge• Electron vs. Ion• Defibrillator

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Figure 1.3-1A simple circuit.

• Charge : quantity of electricity responsible for electric phenomena

• Current : time rate of flow of electric charge past a given point

• Direct current : current of constant magnitude

• Time-varying current : current of varying magnitude

Electric Circuits and Current Flow

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Figure 1.3-3Current in a circuit element.

Figure 1.3-4A direct current of magnitude I.

Figure 1.3-5(a) A ramp with a slope M. (b) a sinusoid. (c) An exponential. I is a constant. The current I is zero for t<0.

Electric Circuits and Current Flow

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Example 1.3-2

Example 1.3-3

Electric Circuits and Current Flow

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Figure 1.5-1Voltage across a circuit element

Figure 1.6-1(a) The passive convention use for

element voltage and current. (b) The passive convention is not

used.

Voltage, Power and Energy

• Voltage : energy required to move a positive charge from – to +• Energy : capacity to perform work• Power : time rate of expending or absorbing energy

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Table 1.6-1Power Absorbed or Supplied by an Element

Power and Energy

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Example 1.6-2

Example 1.6-3

Power and Energy

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Figure 1.7-1The problem-solving method.

Circuit Analysis and Design

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Figure 1.7-2An element with a voltmeter and ammeter.

Figure 1.7-3The circuit from Figure 1.7-2 with the ammeter probes reversed.

Circuit Analysis and Design

Example 1.7-1

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Figure 1.9-1An element with a voltmeter and ammeter.

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