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PHYSICS test 5..

Electrostatics the study of electricity at rest.
Atoms Every atom is composed of a positive nucleus surrounded by negative electrons.
What are the 4 fundamental forces? Strong, Electromagnetic, Weak, and Gravity
Coulomb Unit for charge
Electrical Force Decreases as distance increases
Robert Millikan First person to find the charge of an electron
Conservation of Charge Electrons cannot be created or destroyed, just transferred.
Charging Occurs when when transferring electrons from one place to another
Two ways charging can be done Induction and contact
Contact Charging When material rub together, electrons can be transferred.
Charge Polarization When a charged object is brought near an insulator, there are no free electrons to migrate.Instead there is a rearrangement of charges within the material.Example: balloons
Induction Charging This occurs when an object is brought close to a charge and then grounded or separated.
Conductor A material that allows electrons to flow freely is a good conductor of electricity
What is the best conductor Silver, copper is also good, and cheaper
Insulator A material that doesn't allow electrons to flow Examples: glass, air, wood
Semiconductors Can be made to behave like both conductors and insulators
Superconductors Allow zero resistance to the flow of charge. Once the flow starts, no energy is lost to heat. Extremely cold temps are required
Electric Potential It takes energy to push a charged particle against an electric field. Also known as voltage.
Electric Storage Capacitors can store charges after the current has stopped and be discharged when a conductive path is provided.
Van de Graff Generator Positive charges are built up on the metal sphere and discharge when brought close to the small negative sphere.
How does lightning work? The negatively charged clouds induce a positive charge on the Earth’s surface. When enough charged builds, it produces an electrical discharge.
Voltage Electric pressure
Current Charges flowing through a circuit
Flow of Charge Electrons flow from the negative terminal to the positive
Resistance How much current depends on the voltage but also on the electrical resistance. More resistance = less current.
What is resistance measured in? Ohms
Ohm's law current is directly proportional to the voltage in and circuit and inversely proportional to the resistance. V=IR
Series Circuit Current has only 1 pathway Each resistor gets part of the voltage More resistors, more resistance If one device breaks, all current stops
Parallel Circuit Current has more than one pathway Each resistor gets all of the voltage More resistors, less resistance If one device breaks, current continues in the others
What causes electrical shock? Current
Electrical Power The rate at which electric energy is converted into another form.
P=IV Electrical power
Direct Current (DC) Refers to flowing charge in one direction. Example: batteries
Alternating Current (AC) When electrons are moving back and forth. Has a frequency of 60 Hz
Oscilloscope A device used to graph voltages vs. time or other voltages
Diode Only allows current to flow in one direction. Converting AC to DC
Capacitor Stores a charge between two plates
How does an LED work? When the positive of a battery is hooked to the N side, no current flows
4 Natural elements that are magnetic? Iron, cobalt, nickel and gadolinium
Source of all magnetism? Due to the motion of charged particles
Magnetic Fields The lines from pole to pole surrounding a magnet. Start at north and end at south
Neodymium A rare earth element that can be made into very strong magnets because of its 4 unpaired electrons.
Electromagnets A coil of wires carrying a current.
Charged particles If this is moving through a magnetic field, it deflects.
Electrical forces opposites attract, like forces repel
Power The rate at which electrical energy is changed
Fuse Breaks the circuit if too much current flows
What happens when there is a short circuit? Current will travel through a short instead of through anything that has resistance.
Solar Wind Charged particles flowing from the sun.
Magnetic Field The lines from pole to pole surrounding a magnet.
What is the source of magnetism? Spinning motion of electrons.
How does the Earth have a magnetic field and which direction does it flow? Moving currents of molten iron in the core. It goes from the south pole to the north.
What happens when a current travels in a coil of wire? It induces a magnetic field (electromagnet)
Galvanometer A coli of wires that depending on the voltage deflects a certain amount.
Northern Lights When cosmic rays collapse the Earth’s magnetic field.
Generator Mechanical energy transformed into electrical energy. Uses a coil of wire and a magnet.
Transformer Is used to step up voltages and reduce current so electricity can be transported over long distances. When it arrives another transformer steps it back down.
What happens when you move a magnet through a coil of wires? It induces a short burst of current in the wires.
Why did Nikola Tesla invent AC? Because DC requires high current witch requires larger wires and many of them. Also it cannot be transported long distances.
Faraday's Law An electric field is induced in any region of space in which a magnetic field is changing.
Maxwell's Counterpart to Faraday's Law A magnetic field is induced in any region of space in which an electric field is changing.
Created by: elizabethlauren