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Chapter 1Basic Electric Circuit Concepts

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BASIC CONCEPTS

LEARNING GOALS

System of Units: The SI standard systemSysteme International unit (=International System of Units)()

Basic Quantities: Charge, current, voltage, power and energy

Circuit Elements: Active and Passive

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http://physics.nist.gov/cuu/index.html

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Information at the foundation ofmodern science and technologyfrom the Physics Laboratory of NIST

Detailed contents

Values of the constants and related informationSearchable bibliography on the constants

In-depth information on the SI, the modernmetric system

Guidelines for the expressionof uncertainty in measurement

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SI DERIVED BASIC ELECTRICAL UNITS

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CURRENT AND VOLTAGE RANGES

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Strictly speaking current is a basic quantity and charge is derived. However,physically the electric current is created by a movement of charged particles.

+

++

)(tq

+

What is the meaning of a negative value for q(t)?

PROBLEM SOLVING TIPPROBLEM SOLVING TIPIF THE CHARGE IS GIVEN DETERMINE THE CURRENT BYDIFFERENTIATIONIF THE CURRENT IS KNOWN DETERMINE THE CHARGE BYINTEGRATION

A PHYSICAL ANALOGY THAT HELPS VISUALIZE ELECTRICCURRENTS IS THAT OF WATER FLOW. CHARGES ARE VISUALIZED AS WATER PARTICLES

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+

++

)(tq

+

EXAMPLE

])[120sin(104)( 3 Cttq =

=)(ti )120cos(120104 3 t ][A

][)120cos(480.0)( mAtti =

EXAMPLE