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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. +. -.
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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
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 / D2
ACTIVITY POLARIZING A STICK
Polarization • Polarized objects have an uneven distribution of charge. • A polarized object has no net charge. - - - - - - - - - - - - - - - - - - - - - Meter Stick + + + + + + + + + + + + + + + + + + + +
- - - - - - Weak Force - - - - - - - - - - - - - - - - - - - - - + + + + + + + + + + + + + + + + + + + + Strong Force
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: • 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 1.5 VOLTS -TERMINAL + 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.