Positive and negative (also explains attraction and repulsion)
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Are electric charges created or destroyed?
NEITHER; bc it is conserved
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Is charging the separation or creation of electric charges?
Separation
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How are objects charged?
Transfer of electrons
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What type of charge does an area have with an excess of electrons?
Negative charge
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What type of charge does an area have with a deficit of electrons?
Positive charge
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What happens to charges when they are added to one part of an insulator?
They remain on that part
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Insulator examples
Glass, fabric, rubber, wool, dry wood, most plastics, and dry air
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What happens to charges when added to a conductor?
They spread quickly throughout the conductor
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Conductor examples
Graphite, metals, water, and and matter in the plasma state
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Under certain conditions can charges move through a substance that is ordinarily an insulator?
Possibly, an example is lightning
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Protons
\+
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Electrons
\-
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What happens in a neutral object?
Same # of protons and electrons (total charge
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Charging by friction
(by touch) rub two objects together, the electrons transfer, one object becomes more negative, the other more positive
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Materials that tend to gain electrons
Rubber and plastic
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Materials that tend to lose electrons
Wool/fabric, hair, and glass
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Electrostatic fore acts over a…
Distance
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As the distance increases how does the charge in the electrostatic force act?
Increases
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Charging by conduction
Charges a neutral object by touching that object with a charged object
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What does conduction require?
The transfer of electrons between the charging object and the object being changed
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Charging by induction
charges a neutral object by bringing a charged object near a neutral object without the two objects touching
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Induction
Makes use of separation of charge or grounding to charge a neutral object
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What does charging by induction enable?
The charging object may be used multiple times
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What does Coulomb’s Law state?
The force between two charged particles varies directly with the product of their charges and inversely with the square of the distance between them
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What is Coulomb’s law used for?
To find the magnitude of the force two charged particles exert on each other
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Grounding
Having a way for electrons to leave or enter a situation when too much charge is built up
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Explain why having a third grounding prong on electronics makes them safer
Large electronics have a prong that connects to the grounding wire that leads under the building into the arch, this causes the charges to not building up causing a less chance of shock/fire
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Electric current
A flow of charged particles
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Current direction
The direction in which a positive test charge moves
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Circuit
Transforms electrical energy some other form of energy
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Ohms Law
States that the voltage is directly proportional to the current and the resistance is inversely proportional to the current
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Electricity
A flow of electrons or charges
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Current
Measure of how fast electrons are moving through a wire
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Circuit
Any closed loop or do cutting path allowing electric charges to flow
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Voltage
A measure of how strong a difference in charge is (like electric pressure)
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Charge pump
Provides this difference in charge
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Resistance
A measure of how much a resistor resists the flow of electricity
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Resistor
Limits the current that can flow through
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Water pipe analogy: Electricity
Water
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Water pipe analogy: Wire
Pipes
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Water pipe analogy: Current
Current (rate @ which water flows)
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Water pipe analogy: Charge pump
Water pump (makes water flow)
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Water pipe analogy: Voltage
Water pressure
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Water pipe analogy: Switch
Nosel or faucet (turns water on and off)
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Water pipe analogy: Resistor
Rocks/blockages
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Water pipe analogy: Resistance
Decrease in current due to blockage
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If there is more than one resistor how is a current determined?
By the voltage of the battery and the quivalent resistance in the circuit
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How is resistance determined in SERIES?
The sum of the resistance of its parts
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How is resistance determined in PARALLEL?
The reciprocal of the sum of the reciprocals of the individual resistances
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What poles do magnets have?
North and south
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Like poles….
Repel
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Unlike poles….
Attract
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Can north and south poles exist w/o the other?
No
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Domain
The smallest magnetic unit, or smallest magnetic particle
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Ferromagnetic materials become magnetic when
Their domains are in alignment with eachother
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Why is a magnetic field a vector quantity?
They have direction and magnitude
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Where can a magnetic field exist?
In any region of space also any current-carrying wire
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How can magnetic fields be represented?
By field lines which exit from a North Pole and enter at a South Pole, forming closed loops
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How are permanent magnets made?
Melt down a ferromagnetic material in the presence of a strong magnet so domains align. Allow the material to cool and harden (while the strong magnet is still there). Now all of the domains will remain aligned and forever suck in this magnetic orientation.
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Explain how the right hand rule describes the direction of the magnetic field around a current-carrying wire
If your thumb of the right hand is pointing in the direction of the current, the magnetic field lines loop in the direction of your fingers wrapping around the wire.
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Explain how an electromagnet is made
Take wire and make a bunch of loops, run the current through the wire, all of the magnetic fields add up, you get a magnetic field similar to a permanent magnet
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Explain how the other right hand rule describes the pole of an electromagnet and the direction of the current
Wrap fingers in direction of current, thumb will point to the North Pole of the electromagnet
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Magnetic fields
A region of space surrounding a magnet where a magnet exerts a force
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Magnetic Field Lines
Field lines merge from a magnets North Pole and enter its South Pole. The field line form closed loops, continuing through the magnet from its South Pole to its North Pole.
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Direction of magnetic field
Is the direction in which the North Pole of a compass points when placed in the magnetic fields
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Ferromagnetic materials
Iron, nickel, and cobalt
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How is a temporary magnet created?
A ferromagnetic material is brought into a magnetic field aligning domains
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