Electric Current PowerPoint

Bell Ringer 

Grab the following 

1 wire

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1 light bulb

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1 battery

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Using just this material. Light the light bulb.

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Draw what you did.

Bell Ringer 

What is another term for potential electrical difference?

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What is the definition of electrical current?

Circuits 

Closed Circuit  llows a complete path for electrons to tra!el

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"pen Circuit 

Does not allow a complete path for the electrons to tra!el

Flow of Charge 

#otential Difference$ When the ends of an electric conductor are at different electric potentials %!oltages&

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Charge continues to flow until the ends of the conductor has the same !oltage

Flow of Charge

Flow of Charge

Electric Current 

'lectric Current$ (he flow of electric charge 

(he loosely bound outer electrons of conductors carry the charge through circuits

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#rotons tightly bound to the nuclei of atoms

Electric Current current ) charge * time or  + ) ,*t 

Units$ mps %&  n amp is the flow of 1 C of charge per second

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-"('$ 1 C ) the charge of /02/222/222/222/222/222 electrons

Electric Current 

Usually the number of electrons entering a wire is the same as the number lea!ing 

(his gi!es the wire a net charge of 3ero

Voltage Sources 

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4oltage 5ource$  de!ice which pro!ides a potential difference in order to 6eep current flowing 

Dry*Wet Cells$ Con!ert chemical energy to electrical energy

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Generators$ Con!ert mechanical energy to electrical energy

(he !oltage a!ailable to electrons mo!ing between terminals is calle electromoti!e force/ or emf .

Voltage Sources -ote$

4oltage flows across a circuit

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Current flows through a circuit

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Bell Ringer 

Which object yielded the highest potential difference?

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Which arrangement yielded the most potential difference?

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What are two types of !oltage sources?

Current vs. Voltage 

Current 7 8low rate 9easured in mperes

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 mount of flowing water 

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4oltage 7 #otential 9easured in 4olts

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Water #ressure

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Electric Resistance 

'lectric :esistance$ (he ability of a material to resist the flow of charge 

Units$ "hms %Ω&

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(he amount of charge that flows through a circuit depends on two things$ 4oltage pro!ided by source

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'lectric resistance of the conductor 

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Bell Ringer 

Why are light bulbs more li6ely to burn out when they are first turned on as opposed to burning out after being on for a long period of time?

Resistors

Bell Ringer 

What is the resistance of this resistor?

Resistance in a Wire

Electric Resistance Factors 

(hic6 wires ha!e less resistance than thin wires

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5hort wires ha!e less resistance than long wires

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;igher temperatures usually cause more resistance 

(he resistance in some materials becomes almost 3ero at !ery low temperatures

Ohm’s Law 

(he current in a circuit is 

Directly proportional to the !oltage across the circuit

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+n!ersely proportional to the resistance of the circuit

(herefore$ Current ) 4oltage*:esistance or 

+ ) 4*:

Ohm’s Law: Samle !ro"lems 

;ow much current flows in a 1222  through a 1=