STATIC
ELECTRICITY
THE STUDY OF
CHARGES AT REST
ACTIVITY
MODEL OF AN ATOM
CHARGE A BALLOON
STATIC ELECTRICITY
When you rub a balloon on your hair you
scrape electrons off the atoms of your hair
onto the balloon.
The atoms of the balloon apparently have
more “grab” on electrons.
“Laws of Attraction”
Opposite Charges Attract
+
-
Like Charges Repel
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ACTIVITY
STYROFOAM
ELECTROSCOPE
A COULOMB
THE FUNDAMENTAL UNIT
OF CHARGE
IT IS EQUAL TO THE
CHARGE OF 6.25 BILLION
BILLION ELECTRONS
COULOMBS LAW
ELECTRICAL FORCE
DEPENDS ON THE SIZE
OF THE CHARGES AND
THE DISTANCE
BETWEEN THE CHARGES
Coulomb’s Law
The force between charges varies
inversely with the square of their
separation distances.
+
+
+ +
COULOMB’S LAW
F = k X Q1 X Q2 /
2
D
ACTIVITY
POLARIZING A STICK
Polarization
Polarized objects have an uneven
distribution of charge.
A polarized object has no net charge.
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Meter Stick
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Weak Force
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Strong Force
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CURRENT
ELECTRICITY
THE STUDY OF
CHARGES IN
MOTION
ELECTRICAL CIRCUIT
A COMPLETE PATH
FOR ELECTRON
FLOW
ACTIVITY
ELECTICAL ALTERNATIVES
XMAS TREE BULB
MAKE A WIRE
CIRCUIT WIRE
CONDUCTOR
INSULATOR
ELECTRICAL CIRCUIT
CONSISTS OF
•SOURCES OF ELECTRICAL ENERGY
•A COMPLETE CONDUCTING PATH
•DEVICES THAT CONVERT
ELECTRICAL ENERGY TO OTHER
FORMS
ACTIVITY
ADDING BATTERIES
MAKE A SWITCH
What is a conductor?
a material that allows free electron
movement
Examples:


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Aluminum
Gold
Copper
All Metals
ACTIVITY
GOOD CONDUCTORS
POOR CONDUCTORS
What is an insulator?
a material that does not allow electrons
to flow freely
Examples:



Plastics
Ceramics
Amber
ACTIVITY
CONDUCTIVITY
TESTER
LIGHT BULB
FILAMENT
CONDUCTOR
ACTIVITY
CREATING LIGHT
BATTERIES
- TERMINAL
1.5 VOLTS
+ TERMINAL
STANDARD “D” CELL
VOLTAGE
COMMON TERM FOR
“POTENTIAL”
THE AMOUNT OF ENERGY PER
ELECTRON PRODUCED BY AN
ENERGY SOURCE (BATTERY)
ELECTRICAL
CURRENT
THE RATE OF FLOW OF
CHARGE
ELECTRICAL CURRENT
THE BRIGHTNESS OF A LIGHT BULB IS
A GOOD INDICATOR OF THE RELATIVE
AMOUNT OF CURRENT FLOWING
THROUGH IT.
ELECTRICAL CURRENT
ELECTRONS FLOW OUT OF THE
NEGATIVE TERMINAL OF A BATTERY.
AFTER ELECTRONS TRAVEL
THROUGH THE CIRCUIT, THEY FLOW
INTO THE POSITIVE TERMINAL OF THE
BATTERY.
ELECTRICAL
RESISTANCE
RESISTANCE TO ELECTRON
FLOW
ACTIVITY
PENCIL LEAD DIMMER
SWITCH
LIGHT DIMMER
ELECTRICAL SHORT
A LOW RESISTANCE PATH ACROSS THE
TERMINALS OF AN ELECTRICAL
CIRCUIT ELEMENT.
IF IT OCCURS ACROSS A BATTERY,
GENERATOR OR ANY ENERGY
SOURCE, IT CAN CAUSE TOO HIGH OF
A CURRENT.
ELECTRICAL SHORT
SOMETIMES A RESISTOR CAN HAVE A
SHORT ACROSS ITS LEADS. IF THIS
OCCURS AND ANOTHER RESISTOR IS
IN THE CIRCUIT, THE OTHER
RESISTOR MAY POSSESS ENOUGH
RESISTANCE TO KEEP THE CURRENT
FROM BECOMING TOO LARGE. WHEN
THIS OCCURS, NO CURRENT WILL
PASS THROUGH THE SHORTED
RESISTOR.
CIRCUIT DIAGRAM
A CONCISE REPRESENTATION
OF AN ELECTRICAL CIRCUIT
UTILIZING STANDARD
ELECTRICAL SYMBOLS.
IT SHOULD BE ACCURATE,
SIMPLE AND NEAT.
ACTIVITY
ELECTROSQUARES
DRAWING CIRCUITS
ELECTRON CURRENT
A MEASURE OF THE RATE OF FLOW
OF ELECTRON CHARGE THROUGH A
CIRCUIT.
THE DIRECTION OF FLOW IS FROM
THE NEGATIVE SIDE OF THE ENERGY
SOURCE THROUGH THE CIRCUIT TO
THE POSITIVE SIDE OF THE ENERGY
SOURCE.
OHM’S LAW
THE CURRENT THROUGH A RESISTOR
IS PROPORTIONAL TO THE APPLIED
VOLTAGE AND INVERSELY
PROPORTIONAL TO ITS RESISTANCE.
I=V/R
I = CURRENT
V = VOLTAGE
R = RESISTANCE
ELECTRICAL CURRENT
• A MEASURE OF THE NUMBER OF
COULOMBS PER SECOND THAT
PASSES A POINT IN A CIRCUIT.
• THE UNIT OF CURRENT IS THE
AMPERE = COULOMB PER SECOND
VOLTAGE (POTENTIAL)
THE ENERGY PER CHARGE LOST OR
GAINED BY CHARGES AS THEY PASS
THROUGH A DEVICE.
THE UNIT IS THE
VOLT = JOULE PER COULOMB
RESISTANCE
A MEASURE OF THE RESISTANCE
TO ELECTRON FLOW.
THE UNIT IS THE
OHM = VOLT PER AMPERE
SYMBOL FOR OHM IS W
RESISTANCE
RESISTANCE CAN BE RELATED TO
THE AMOUNT OF VOLTAGE NEEDED
TO PRODUCE A AMPERE OF CURRENT.
IF IT TAKES TWO VOLTS TO PRODUCE
ONE AMPERE, THE RESISTANCE IS
TWO OHMS
Current, Voltage, Resistance
Current


a measure of the rate of flow of electrons
measures in Amperes (A)
Voltage


a measure of the energy per charge
measured in Volts (V)
Resistance

a measure of the resistance to electron flow

measured in Ohms (W)
SERIES CIRCUITS
THE CURRENT HAS A
SINGLE PATH
AROUND THE
CIRCUIT
ACTIVITY
SERIES CIRCUIT
CIRCUIT ELEMENTS
IN SERIES
ALL HAVE THE SAME
CURRENT
THROUGH THEM
PARALLEL CIRCUIT
THE CURRENT HAS
MULTIPLE PATHS
AROUND THE
CIRCUIT
ACTIVITY
PARALLEL CIRCUITS
CIRCUIT ELEMENTS
IN PARALLEL
ALL HAVE THE SAME
VOLTAGE ACROSS
THEM
RESISTORS IN SERIES
THE TOTAL RESISTANCE IS
THE SUM OF ALL
RESISTORS IN SERIES.
RESISTORS IN PARALLEL
THIS COMBINATION
POSSESSES LESS COMBINED
RESISTANCE THAN THE
LOWEST RESISTOR IN THE
COMBINATION.
BATTERIES IN SERIES
THE TOTAL VOLTAGE
PRODUCED BY BATTERIES IN
SERIES IS THE SUM OF THE
VOLTAGES OF EACH BATTERY
BATTERIES IN PARALLEL
PRODUCE THE SAME
VOLTAGE
QUESTION
HOW DO YOU CONNECT A BATTERY TO
“JUMP START” YOU CAR?
WHY ARE BATTERIES CONNECTED IN
BOTH PARALLEL AND SERIES IN SOME
PORTABLE DEVICES?
ACTIVITY
ELECTRIC CIRCUITS
DIODE
DIODE MEANS TO CONDUCT IN
ONLY ONE DIRECTION
WILL CONDUCT
ELECTRONS
WILL NOT CONDUCT
ELECTRONS
LIGHT EMITTING DIODE (LED)
A DIODE THAT EMITS LIGHT
WHEN CURRENT IS PRESENT.
MOST LED’S REQUIRE ONLY A
MILLIAMP TO BE SEEN.
FUSE
A FUSE IS PLACED IN SERIES
WITH THE ENERGY SOURCE.
IT IS RATED TO BURN (OR
MELT) IF THE CURRENT
THROUGH IT EXCEEDS ITS
RATING.
ACTIVITY
CIRCUIT BREAKERS
CIRCUIT BREAKER
A MAGNETIC SWITCH THAT
BREAKS THE CIRCUIT IF
THE CURRENT IN THE
CIRCUIT EXCEEDS ITS
RATING
SWITCHES
SINGLE POLE SINGLE THROW
SINGLE POLE DOUBLE THROW
ACTIVITY
MAKE A SWITCH
LEMON BATTERY
THE ZINC TERMINAL IS NEGATIVE
THE COPPER TERMINAL IS POSITIVE
ABOUT 1 VOLT IS PRODUCED BY A SINGLE
LEMON BATTERY
YOU NEED TWO LEMONS TO LIGHT AN LED
ACTIVITY
LIGHT AN LED USING
LEMON BATTERIES