electrostatics

What is static electricity? PG471
* Static electricity is an imbalance of electric charge on the surface of an object
* Electric charge is a property of the particles of atoms. Protons (positive), electrons (negative), neutrons (no charge)
* Electrons can be added or removed from atoms
* 2 materials come in contact, electron transfer may occur, imbalance in charge
* Neutral objects, equal number of protons and electrons
* Become positively charges when lose electrons (more protons than electrons)
* Become negatively charged when gain electrons (more electrons than protons)
* Law of Electric Charges: like charges repel, unlike charges attract
* Charged object can be used to induce charge separation in neutral object
* Metal leaf electroscope, detect electric charge
Charging by Contact PG477
* Charging by friction- 2 neutral objects of different materials rub/touch each other, electron transfer
* Charged by friction, 1 material more likely to accept electrons, 1 more likely to give up electrons (some atoms more strongly attracted to electrons than others)
* Electrostatic series- list that ranks tendency of different materials to gain electrons, predict charge when materials come in contact
* Charging by conduction- 2 objects with different # of electrons contact, electrons transfer from 1 object to another
* Neutral object charge by conduction, gets same charge as charged object
* 2 charged objects, different electric charges come in contact, electron transfer
* Ground objects- transfer electrons between object and large neutral object
Conductors and insulators PG482
* Conductors- allow electrons to pass through them easily
* Insulators- inhibit/prevents the movement of electrons
* Semiconductors- special properties, fair conductors
* Example: laser printer
Charging by induction PG489
* Temporary charge imbalance in neutral object when charged object is near
* Charged permanently by induction, bring charged object near neutral object then ground neutral object
* Charging by induction- separation of charge in the object that is charged
* Example: electrostatic loud speakers, lifting footprints
Electric discharge PG495
* Electric discharge- rapid transfer of electrons from 1 object to another
* Can produce visible sparks
* Example: lightning
* Lightning rods used to safely direct lightning into the ground
Introducing current electricity PG508
* Static electricity- movement of electrons in uncontrolled way
* Current electricity- controlled flow of electrons through conductor
* Moves easily though conductors, poorly through insulators
* Needs source of electrical energy to create flow of electrons
Electric circuits PG510
* Electric circuit- continuous path that allows flow of electrons. Energy source, conducting wires, load and switch
* Energy sources include batteries and generating stations
* Load: any electrical device that converts electrical energy into other forms of energy. Example: light bulb
* Switch- enable you to turn circuit on/off
Circuits and circuit diagrams PG554
* Circuits can be represented using diagrams and circuit symbols
* Loads can be connect in series/parallel
* Only 1 path for electrons to follow in series circuit
* More than 1 path in parallel circuit
Electric circuit PG557
* Current- measure of the rate of electron flow past a given point in a circuit
* Measured in amperes (A) using ammeter
* Ammeter must be connect in series with load when measuring current
* Circuit breakers/fuses protect electrical devices from excess current
* Small amount of electric current can be dangerous to human body