Current Electricity.notebook
January 20, 2016
Current Electricity
Electric Current ~ the movement of electric charges from one place to another. We know that electrons can flow freely through conducting material. Thus, electric current is the amount of charge that moves past a given point in a conductor per second. Charges move due to repulsion from the next electron in line.
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Current Electricity.notebook
January 20, 2016
I = Q / t where Q = total charge in Coulombs (C)
I = current in amperes (A)
t = time (s)
1 ampere is the electric current when 1 coulomb of charge moves past a point in a conductor in 1 second.
Note: Ampere = C/s
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Current Electricity.notebook
January 20, 2016
Direct Current (DC)
electric current which flows in one direction only. i.e. a battery produces direct current. The electrons cannot reverse their direction of flow. Positive and negative terminals are fixed.
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http://www.ndt­ed.org/EducationResources/HighSchool/Electricity/directcurrent.htm
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Current Electricity.notebook
January 20, 2016
Alternating Current (AC)
Electric Currents in which electrons change direction many times per second (60 times per second, 60 Hz)
i.e. type of power supplied to homes and factories by power stations. It is easier to send alternating currents over long distances. The electrons move back and forth along the wire 50­60 times a second.
http://www.ndt­ed.org/EducationResources/HighSchool/Electricity/alternatingcurrent.htm
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Current Electricity.notebook
January 20, 2016
Ammeter ~ device used to measure electric current. Must be placed in the stream of the current.
Galvanometer ~ a type of ammeter used to detect and measure a "small" electric current.
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Current Electricity.notebook
January 20, 2016
Some confusion about current (two theories)
1. Electron Flow Current ~ used by physicists. The current direction is the same as the direction of electron flow.
i.e. from negative to positive terminal.
2. Conventional Current ~ states that current flows in the opposite direction as the electrons i.e. from the positive to the negative terminal.
Electron Flow Current
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Conventional Current
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Pg 548 # 2­4, pg 575 # 9,10 Read and make notes on pg 533­535
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