Download Electricity Continued SHORT versionR2014

GPS
•
S8P5. Students will recognize
characteristics of gravity, electricity,
and magnetism as major kinds of
forces acting in nature.
 Demonstrate the advantages and
disadvantages of series and parallel
circuits and how they transfer energy.
EQs
How are electric circuits wired?
What exactly is electricity?
What are the advantages and
disadvantages of series and
parallel circuits?
How do they transfer energy?
Electricity is the movement of electrons
• Atoms contain charged particles known as protons
(+) and electrons (-)
• Like charges repel
• Unlike charges attract
Electrons move from an area that is negatively
charged (extra electrons) to an area that is
positively charged (wanting electrons).
Unlike charges attract
Like charges repel.
Electricity
Electricity occurs in 2 different
forms
1. Static
2. Current
Is stationary
Flows around circuit
E.g. Brush your hair
E.g. turn on light
Wool socks in
tumble dryer
Walkman
Static Electricity
Occurs with materials which are
insulators
Rubbing adds or removes electrons
Object becomes charged
Like objects repel, unlike attract
Current Electricity
Electrons flow through a conductor
Negative to positive
Circuit = continuous loop for
electrons to flow
Needs energy supply
Energy user
Series circuit
•
•
•
•
•
Has a single loop for electrons to travel round
Components are connected one after another
Current has to travel through all components
Current is the same at all points
Voltage is shared between components
Uses for Series Circuits Series
circuits are useful in wiring burglar
alarms. If any part of the circuit fails,
there will be no current in the system
and the alarm will sound
Parallel circuit
•
•
•
•
Has two or more paths for electrons to flow down
Current is shared between the branches
Sum of the current in each branch = total current
Voltage loss is the same across all components
Uses for Parallel Circuits
Almost all appliances are built
with parallel circuits so that
they will keep working if part of
the system fails.
Electricity
• Electricity is forced around a circuit by an
electrical force field
• Flow of electricity around a circuit is
called CURRENT (I)
• Current measured in amps (A)
• Voltage (V) – Increase or decrease in the
amount of electrical energy carried by the
current.
Current (I)
• Current is the flow of electrons around a
circuit
• Measured in amperes (amps)
• DC = direct current like battery
• Electrons flow in one direction
• AC = Alternating current like mains
• Electron flow changes direction 50x per
second
Ammeter
• Measures CURRENT (I)
• Unit = Amp (A)
• Current is flow of electrons
• Connect in series at the point you wish to
measure
• RED to RED and BLACK to BLACK
Voltage (V)
• Gain or loss of energy as it passes through
a component
• Voltage lost = voltage gained
• In series voltage loss is shared between
components
• In parallel voltage loss is the same across
all components
Voltmeter
• Measures voltage
• Unit = Volt (V)
• Voltage increases as it passes through
energy suppliers
• Voltage is decreased as it passes through
users
• Connect in parallel around a component
SUMMARY
In Series
Current
Voltage
Always the same
Voltage from source =
voltage used
Voltage is shared
between power users
In Parallel
The branches share
electrons and add to
the total
Voltage is the
same in all
branches
resistance
R
The amount that a component
slows the current or the opposition
to the flow of electric charge.
Resistance is measured in
ohms.
grounding
The creation of a harmless, lowresistance path—a ground—for
electricity to follow. Grounding is an
important electrical safety procedure.
Static Electricity
Electric Discharge The loss of static
electricity as charges move off an object
is called electric discharge. One of the
most dramatic examples of electric
discharge is lightning. The next slide
shows how lightning is formed.
AC and DC There are two kinds of
electric current—direct current (DC) and
alternating current (AC).
Parts of an Electric Circuit
Forming a Loop An electric circuit
is a complete, closed path through
which electric charges flow.
All circuits need three basic parts:
an energy source, wires, and a
load.
A Switch to Control a Circuit
Sometimes, a circuit also contains a
switch. A switch is used to open and
close a circuit.
Circuit Failure Broken wires or water can
cause a short circuit. In a short circuit,
charges do not go through one or more loads
in the circuit.
Fuses A fuse has a thin strip of metal. Fuses
keep charges from flowing if the current is too
high.
Circuit Breakers A circuit breaker is a
switch that automatically opens if the
current is too high. Charges stop flowing.
Electrical Safety Tips Do not overload
circuits by plugging in too many electrical
devices. Do not use electrical devices
near water.