ELEC2110-Lecture _4-Wednesday 1-19-11

# ELEC2110-Lecture _4-Wednesday 1-19-11 - ELEC 2110 Elements...

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ELEC 2110 Elements of Electrical Engineering Lecture # 4 1/19/11 (Wednesday) ) 10 cos( 5 t v s

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LECTURE #4 OUTLINE II – HW #1 DUE WED 1/26/11 III– CHARGE, IV – CIRCUIT ELEMENTS VII – KIRCHHOFF’S CURRENT/VOLTAGE LAWS VIII – EQUIVALENT RESISTANCE
CHARGE Charge is a fundamental physical quantity Charge is an electrical property of the atomic particles of which matter consists Measured in coulombs (C). Types Positive Negative Opposite effects; use + & - signs Electron negative sign Proton Positive sign

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CHARGE The charge e on one electron is negative and equal in magnitude to 1.602 10 -19 C. The charges that occur in nature are integral multiples of the electronic charge. In one Coulomb of charge, there are 1/ 1.602 10-19 = 6.24 10 18 electrons The charge can neither be created nor destroyed, only transferred
The net flow of positive charges . The time rate of change of charge . Electric current i = dq/dt . The unit of ampere can be derived as 1 A = 1C/s . CURRENT

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A direct current (dc) is a current that remains constant with time. An alternating current (ac) is a current that varies sinusoidally with time. (reverse direction) CURRENT
CURRENT The direction of current flow is associated w/ positive charges

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CURRENT Example 1 A conductor has a constant current of 5 A. How many electrons pass a fixed point on the conductor in one minute?
Voltage (or potential difference) is the energy required to move a unit charge through an element, measured in volts (V). Voltage is a signed quantity ( + or -)

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ELEC2110-Lecture _4-Wednesday 1-19-11 - ELEC 2110 Elements...

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