Electricity
Lesson 1
13.3 Electric Current
Series and Parallel Circuits
In series circuits, current can only take one
path.
The amount of current is the same at all points
Series and Parallel Circuits
In parallel circuits the current can take more than one
path.
Because there are multiple branches, the current is not
Series and Parallel Circuits
Sometimes these paths are called branches.
The current through a branch is also called the branch
current.
When analyzing a parallel circuit, remember that the
current always has to go somewhere.
The total current in the circuit is the sum of the currents in
Coulombs Law of Charges
Charged bodies attract or
repel each other with force
Electric Current
Current?
flow
Electric Current
Movement of electric charge Rate of charge movement
Q
I
t
unit
C
Ampere, A
1A=1
10 Quantity Physics symbol Measured in unit
Time t seconds s
Current I Amperes Å
Complete Worksheet
Current and Charge worksheet
Lesson 2
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Potential Energy (difference)
Voltage and Current are vital to
understanding electronics, but they are quite hard to grasp because we can't see them
directly.
Voltage is sometimes described as the 'push'
or 'force' of the electricity, it isn't really a force but this may help you to imagine what is
happening.
Voltage is a measure of the energy carried
by the charge.
Voltage attempts to make a current flow, and
current will flow if the circuit is complete
Will the following circuits work?
Electric Potential
Any point in an electric field is said to
have Electric Potential, V.
However, only a Difference in PE is
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Electric Potential
Voltage is supplied by the battery (or
power supply).
Voltage is used up in components,
but not in wires.
Electric Potential Difference
Voltage is the amount of energy that is gained by
each electron from a source and lost over a load. It is the difference in electrical potential energy
between two points in a circuit.
The unit is joules per coulomb OR the Volt (V)
unit Volt, V J
Voltage in a series circuit
Each separate resistance creates
a voltage drop as the current passes through.
As current flows along a series
circuit, each type of resistor
transforms some of the electrical energy into another form of
energy
Ohm’s law is used to calculate the
Voltage and current
in a parallel circuit
In a parallel circuit the voltage is the same
across each branch because each branch
has a low resistance path back to the battery.
The amount of current in each branch in a
parallel circuit is not necessarily the same.
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Voltage
Voltage is a force that pushes/drives the
electrons/charge
It is also referred to as electromotive force or
difference in potential.
Voltage is measured in volts (v)
Voltage source will have a polarity (negative
and positive side)
Current flows from negative to positive
Advantages of parallel circuits
Parallel circuits have two big advantages over series circuits:
1. Each device in the circuit sees the full battery voltage.
2. Each device in the circuit may be turned off independently without stopping the current
Complete Worksheet
Lesson 3
13.7 and 13.9 Resistance
Analysis of Circuits
Key Question:
Series and Parallel Circuits
Sometimes these paths are called branches.
The current through a branch is also called the branch
current.
When analyzing a parallel circuit, remember that the
current always has to go somewhere.
The total current in the circuit is the sum of the currents in
all the branches.
At every branch point the current flowing out must equal
the current flowing in.
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Resistance
Resistance is the opposing force to the flow
of electrons through a part of the circuit.
Resistance (R)is the opposition to the flow of
an electric current, causing the electrical
What is electrical
resistance
?
36
Ohm’s Law
:
The resistance of an object determines the
Ohm’s Law
V
IR
Current = voltage/resistance
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Resistance
Depends on: Length, cross sectional area,
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The unit for measuring resistance is the
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Resistor
An electronic element
that provides a specified resistance.
A current or voltage
20.1 Adding resistances in series
Each resistance in a series
circuit adds to the total resistance of the circuit.
20.1 Total resistance in a series
circuit
Light bulbs, resistors, motors, and heaters usually have
Calculate current
How much current flows in a circuit with a 1.5-volt
Resistance in parallel circuits
Adding resistance in parallel provides another
path for current, and more current flows.
When more current flows for the same
voltage, the total resistance of the circuit decreases.
This happens because every new path in a
Adding resistance in parallel circuits
Ohm’s Law Summary
Quantity Physics Symbol Measured in Unit
Voltage V Volts V
Complete Worksheet
Resistance in Series and Parallel
Series and Parallel Circuits Summary
Series Parallel
Definition Circuit with one path for electrons to flow through
Circuit with multiple paths for electrons to flow through
Current
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Series and Parallel Circuits Summary
Series Parallel
Definition Circuit with one
path for electrons to flow through
Circuit with multiple paths for electrons to flow through
Current The same
everywhere in the circuit
Split up among the branches of the circuit
Voltage
Series and Parallel Circuits Summary
Series Parallel
Definition Circuit with one path for electrons to flow through
Circuit with multiple paths for electrons to flow
through Current The same
everywhere in the circuit
Split up among the branches of the circuit
Voltage Split up among the loads of the circuit
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Power (it’s Electric!)
Power: Rate at which work is done. OR Rate
at which energy is transformed
Electric Power: The rate at which charge
Electric Power
Electric power can be calculated using the current and voltage.
Power = Current x Voltage
unit watt, W
Complete Worksheet
Potential Difference Mixed word problems