LAST PHYSICS TEST EVER

JUST HURRY TF UP

What are the two kinds of electric charges?

What are the two kinds of electric charges?

Positive and negative (also explains attraction and repulsion)

Are electric charges created or destroyed?

NEITHER; bc it is conserved

Is charging the separation or creation of electric charges?

Separation

How are objects charged?

Transfer of electrons

What type of charge does an area have with an excess of electrons?

Negative charge

What type of charge does an area have with a deficit of electrons?

Positive charge

What happens to charges when they are added to one part of an insulator?

They remain on that part

Insulator examples

Glass, fabric, rubber, wool, dry wood, most plastics, and dry air

What happens to charges when added to a conductor?

They spread quickly throughout the conductor

Conductor examples

Graphite, metals, water, and and matter in the plasma state

Under certain conditions can charges move through a substance that is ordinarily an insulator?

Possibly, an example is lightning

Protons

+

Electrons

-

What happens in a neutral object?

Same # of protons and electrons (total charge

Charging by friction

(by touch) rub two objects together, the electrons transfer, one object becomes more negative, the other more positive

Materials that tend to gain electrons

Rubber and plastic

Materials that tend to lose electrons

Wool/fabric, hair, and glass

Electrostatic fore acts over a…

Distance

As the distance increases how does the charge in the electrostatic force act?

Increases

Charging by conduction

Charges a neutral object by touching that object with a charged object

What does conduction require?

The transfer of electrons between the charging object and the object being changed

Charging by induction

charges a neutral object by bringing a charged object near a neutral object without the two objects touching

Induction

Makes use of separation of charge or grounding to charge a neutral object

What does charging by induction enable?

The charging object may be used multiple times

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

What is Coulomb’s law used for?

To find the magnitude of the force two charged particles exert on each other

Grounding

Having a way for electrons to leave or enter a situation when too much charge is built up

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

Electric current

A flow of charged particles

Current direction

The direction in which a positive test charge moves

Circuit

Transforms electrical energy some other form of energy

Ohms Law

States that the voltage is directly proportional to the current and the resistance is inversely proportional to the current

Electricity

A flow of electrons or charges

Current

Measure of how fast electrons are moving through a wire

Circuit

Any closed loop or do cutting path allowing electric charges to flow

Voltage

A measure of how strong a difference in charge is (like electric pressure)

Charge pump

Provides this difference in charge

Resistance

A measure of how much a resistor resists the flow of electricity

Resistor

Limits the current that can flow through

Water pipe analogy: Electricity

Water

Water pipe analogy: Wire

Pipes

Water pipe analogy: Current

Current (rate @ which water flows)

Water pipe analogy: Charge pump

Water pump (makes water flow)

Water pipe analogy: Voltage

Water pressure

Water pipe analogy: Switch

Nosel or faucet (turns water on and off)

Water pipe analogy: Resistor

Rocks/blockages

Water pipe analogy: Resistance

Decrease in current due to blockage

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

How is resistance determined in SERIES?

The sum of the resistance of its parts

How is resistance determined in PARALLEL?

The reciprocal of the sum of the reciprocals of the individual resistances

What poles do magnets have?

North and south

Like poles….

Repel

Unlike poles….

Attract

Can north and south poles exist w/o the other?

No

Domain

The smallest magnetic unit, or smallest magnetic particle

Ferromagnetic materials become magnetic when

Their domains are in alignment with eachother

Why is a magnetic field a vector quantity?

They have direction and magnitude

Where can a magnetic field exist?

In any region of space also any current-carrying wire

How can magnetic fields be represented?

By field lines which exit from a North Pole and enter at a South Pole, forming closed loops

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.

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.

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

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

Magnetic fields

A region of space surrounding a magnet where a magnet exerts a force

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.

Direction of magnetic field

Is the direction in which the North Pole of a compass points when placed in the magnetic fields

Ferromagnetic materials

Iron, nickel, and cobalt

How is a temporary magnet created?

A ferromagnetic material is brought into a magnetic field aligning domains

Permanent magnet

Remain magnetized

Temporary magnets

Lose magnetism easily