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:zap: Physics 9 - Electricity :zap: - Coggle Diagram
:zap: Physics 9 - Electricity :zap:
Main concepts
Physics
Branch of science, study nature and properties of matter and energy
Forms of energy
Light, sound, heat, chemical, electrical, nuclear
Electricity
Flow of electric charge, movement of electrons from one atom to another
Two types: static and current
Electric charge
Created when electrons gained/lost
Gained = negative, lost = positive
Conductors and Insulators
Conductors = copper, aluminum, steel;
Insulators = wood, rubber, plastic
Static electricity
The buildup of negatively charged electrons in an object where there is no path to leave
Created by separation/imbalance of charges
Static charge laws
Opposite charges attract, like charges repel, charged and neutral attract
Charging by friction
One way to create imbalance of charges is by rubbing objects together
Electrons are transferred, losing = positive, gaining = negative
Triboelectric series
Link to
IMAGE
Nylon polyester rub together = nylon positive, polyester negative
Charging by conduction
Occurs when charged objects come in physical contact with neutral objects
When negative object physically contacts neutral object, electrons are transferred to neutral object
negative object stays negative with lower negative charge; neutral object becomes negatively charged
When positive object physically contacts neutral object, electrons are transferred from neutral object to positive object
positive object stays positive with lower positive charge; neutral object becomes positively charged
Charging by induction
Creating charge in objects without contact
When charged objects are moved closer to neutral objects, the opposite charges in neutral obj move closer to the charged obj, and the like charges in the neutral obj repel away from the charged obj
opposite charged surfaces are formed on the neutral object
Electroscope
Instrument used to detect static charge using the concept of charging by induction
When a charged object is moved closer to the ball, the opposite charges attract and come to the top, like charges go down to the metal leaves and will repel/separate
Van de Graaff
Scientific instrument used to generate static electricity
Inside the big metal ball at the top of the generator, positive charges are building up
Current electricity
Flow of electrons in a electrical circuit
Electrical circuit
Path for current electricity to flow from its source and back
4 parts: power source, conducting wires, load/device, switch
Schematic diagrams
Use symbols to represent the parts of an electrical circuit without drawing
Resistors
Used to control the amount of current in the circuit, flow is reduced
Any electrical appliance/device - ex. lightbulb, converting electrical to light energy
Series and Parallel electrical circuits
Series = 1 path, parallel = multiple paths
Types of current:
Alternating Current (AC)
Electrons continuously reverse directions when they flow through circuit (ex. household outlets)
Direct Current (DC)
Electrons flow in only one direction (ex. battery)
Circuit protection
Fuses
Devices used to protect circuit from current surges
Current surges damage expensive devices/cause fires
Set to allow max amount of current; if cross amount, thin wire in fuse will heat up and melt, breaking circuit
Breakers
Works like fuses, but don't need to be replaced, only reset
Made up of a switch, which is triggered to break/open position when current surges above safe amount
Reset: switch must be manually put back into position to allow current to flow again
Electrical grounding
Provides a backup pathway for excess electricity in circuits to flow to the ground
Circuit is connected to the ground through a grounding rod
Appliances are grounded in case of short circuit, an unsafe situation where electricity leaves the wires
More concepts
Voltage
Amount of electrical potential energy in one coulomb of charge, measured in Volts (V)
By separating protons from electrons, we can create electrical potential energy in power sources (battery)
Coulomb is the measurement of electrical charge
Pressure created to push electron flow around the circuit
Higher the voltage of the power source, more current can flow through the circuit
When multiple cells connected in series, voltages accumulate = sum of each cell voltage
When multiple cells connected in parallel, voltages stay constant (no sum)
Current
Amount of charge passing through a point per second, measured in Amperes/Amp (A)
Water hose analogy states: water = charge, water pressure = voltage, measure of waterflow = current
Resistance
Ability of substances to slow down the flow of current in a circuit, measured in Ohms (Ω)
All circuits through which current flows will have some resistance
Resistors are devices added to a circuit to slow down/reduce flow of current
Any electronic device that converts electrical energy into another form of energy can be classified as a resistor
Ohm's Law
Relationship between voltage, current, and resistance in a circuit (V = IR)
States that current in the circuit is directly proportional to voltage, but inversely proportional to resistance
Kirchhoff’s Laws
Kirchhoff’s Current Law (KCL)
Helps determine current at different points in a circuit
States that current entering node/junction = current leaving that same node/junction
When the loads are connected in series, the current is the same through each load and throughout the circuit
When the loads are connected in parallel, the sum of the current at each load is equal to the current that enters the junction
Kirchhoff’s Voltage Law (KVL)
Helps determine voltage at different points in a circuit
States that the algebraic sum of voltages in a circuit is equal to zero
The voltage that's supplied is equal to the sum of voltage drops in the circuit
When the loads are connected in series, the sum of the voltage drops at each load is equal to the total voltage supplied by the power source
When the loads are connected in parallel, the voltage drops at each load is equal to the total voltage