Ohm’s Law
Potential Difference (V)
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Electric Current
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Current (I)
If a charged object is in an electric field it has _______________________________,
that is it has the ___________________________________________________________________
Potential Difference- represents the ____________________________________________
_____________________________________________________________________________________
• Also called the ______________________________________ (the force that
______________________________________), and _____________________________.
• Measured in __________________________ or
____________________________________________
The ______________ of charged particles, caused by a
____________________________________________________________
Defined in terms of the moving of a ___________________________charge
The current travels from _______________________ to _______________________
terminals
________________________
Measured in __________________________ or __________________
I=
q = the amount of charge in Coulombs
that passes a point when a current of one
ampere flows for 1 second
Calculate the current if a
charge of 5.60 C passes
through a point in a
conductor in 15.4 s.
Resistance (R)
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Ohm’s Law
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The amount of electric potential needed to force a given amount of current
through an object
Or
______________________________________________________________________________________
Measured in __________________
Ohm’s Law states that an object has an ability to
________________________________________________ flowing through it. The more
resistance an object has, the more _________________________ you need to force
__________________________ through it. Or, for a given voltage, the more
resistance an object has, the __________________ will flow through it.
V=
V=Voltage (volts)
I=Current (amperes)
What is the potential
difference across a
conductor to produce a
current of 8.00 A if there is
a resistance in the
conductor of 12.0 Ω?
Power (P)
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R=Resistance (ohms)
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The rate ___________________________________________
The rate that work is done on a ____________________________________ in an
__________________________________________
Measured in
_________________________________________________________________________________
P=
P=power (watts)
I=current (amps)
V=voltage (volts)
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Unit for Power
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Electric Power is normally measured in kilowatt-hour
To convert watts to kilowatt-hour multiple
__________________________________________ and divide by ______________________
500 watts in 8 hours would be
What is the power when a
current of 30 amps flows
through a wire with a
resistance of 3 ohms?
Conductivity
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Resistance
A property of a material that depends on the availability of charges that are
relatively free to move under the influence of an electric field
All materials have different conductivity
Metals have many electrons that are free to move-good conductors
Nonmetals electrons are tightly bound-good insulators
Depends on
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Summary
Ohm’s Law Continued/ Intro to circuits
Direct Current
Graph
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Alternating Current
Graph
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Energy in a Circuit
Batteries Use __________________________ energy to give electrons
_____________________________________________
The chemical energy is eventually _____________________________and current
can not travel far
Electrons always flow in _______________________________________
Generators change _________________________________________ energy into
______________________________ energy
Electrons __________________________________________________________________
Better for _______________________ electrical energy to your home
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Is the electrical potential energy gained, lost, or unchanged as the
electrons flow through the following portions of the circuit shown:
• A to B
• B to C
• C to D
• D to A
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A set of electrical components connected such that they
________________________________________________________________________________
A schematic diagram or circuit diagrams can be used to show a circuit
A circuit MUST contain an _____________________________(_________), and a
________________________________________________________ to flow
(wire/conductor)
Intro to Circuits
Circuits
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Open Versus Closed Circuits
An Open CircuitA Closed Circuit
Short Circuits
A short circuit is
Load-
Series Versus Parallel
Can Convert electrical energy to
Series
Two or more components
Parallel
Two or more components
Summary
Series Circuits
Series Circuit
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A circuit in which there are two or more components in which the
current has ________________ path
If resistors are in a series then the _____________________________________ is
equal to the _______________________________ of the resistances
Rt=______________________________
A 9.0 V battery is connected to
four light bulbs, as shown at
right. Find the equivalent
resistance for the circuit .
Current in a Series Circuit
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The total current
V=IR
So..
Go back to the last example, find
the current that runs through
the circuit
Kirchoff’s Laws/ Ohm’s Law for
Series Circuits
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There is only one path so the current must
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It=
The total voltage across the battery must
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Vt=
The total resistance in a series circuit is the
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Rt=
Parallel Circuits
Kirchoff’s Laws on
Parallel Circuits
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What about resistance in
a parallel circuit?
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In a parallel circuit the current is _______________, so the current flowing through
each pathway must be ______________________________________________________
It=
In a parallel circuit the voltage is the___________________ throughout the circuit
Vt =
• Why is the voltage the same when resistance is different?
As resistors are added in a parallel circuit the resistance….
Think about the lunch line
It is easier to move through
Equation
A 9.0 V battery is
connected to four
resistors. Find the
equivalent resistance for
the circuit and the total
current in the circuit.
A battery with a voltage
of 24 V is hooked to the
following circuit. The
current running through
the circuit is 1.8 A. R1
has a resistance of 40
ohms and resistor 3 has
a resistance of 60 ohms.
What is the resistance of
resistor 2
Recap of Series Versus
Parallel
Variable
Series
Parallel
Voltage
Current
Resistance
Example
What is the potential difference supplied by the power source in this circuit?

Example
What are the values of V1, V2 and R2in the circuit?
Kirchoff’s Laws Continued
Kirchoff’s First Law
The algebraic sum
Generally speaking, the total current entering a junction
Draw and Complete the example
Solve for the Current if the initial current was 20 Amps.
Kirchoff’s Second Law
The algebraic sum
Generally speaking, it says, around the loop in a circuit
How are work, power, energy, and electricity related?
Electrical Power
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Power is the rate at which work is done
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In mechanics
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For Electrical Power
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To get max power, would you make a series or parallel circuit? Why?
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The amount of electrical energy used is equal to the
_______________________________________________________________________________
For mechanics: W =
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For electrical energy:
A potential drop of 50 volts is
measured across a 250 
resistor. What is the power
developed in the resistor?
Electrical Energy
An Electrical heater draws a
current of 8 amps and has a
resistance of 15 . How much
energy does the heater use in 1
minute?