electric charges
a physical property of matter that causes it to experience a force when placed in an electromagnetic field. Electric charge can be positive or negative.
electrostatics
the study of stationary electric charges.
friction
when object of different types of matter are rubbed together, which produces a static net charge. this transfers electrons from one material to the next, and charges the objects.
electron affinity
a materials ability to hold on to electrons.
electrostatic series
A list of the ability of substances to hold on to their electrons. a substance higher on the list has a weaker (positive) hold on electrons. a substance lower on the list has a stronger (negative) hold on electrons.
law of attraction/repulsion
like charges repel, and opposite charges attract (neutral charges atttract both positive and negative).
conductivity
the ability of a substance to conduct electricity.
charging by contact
when a charged object touches a neutral object. the electrons will move to the whichever object has less electrons, making both objects have the same charge.
insulators
a substance in which electrons cannot move freely from atom to atom. if you rub two objects together, the charges would stay on the spot where you rubbed it. example would be oil, fur, silk
conductor
A substance in which electrons can move freely through the material. they do not hold a static. if a conductor becomes negatively charged, they spread out. an example would be silver or copper.
how to measure an electric charge?
with an electroscope
induction
a charged object can transfer a charge to a neutral object without touching it. only conductors can be charged in the induction process. the electric field of the charged object forces the electrons of the neutral object to move. (if the field is negative, electrons repel. if the field is positive, electrons attract.)
electrical discharge
the release and transfer of an electrical charge. when a charged object is discharged, the excess charges are removed, making it neutral. ex. grounding, discharge at a point.
grounding
charged object is connected to a wire that is also connected to the ground. this allows the excess electrons to flow from the objects into the earth.
difference between static and current electricity
statis is stationary, and current is moving through a circuit.
potential difference/voltage units
unit- volt
measured with- voltmeter
represented by variable- V
current units
unit- A (ampere)
measured with- ammeter
represented by the variable- i
resistance units
unit- Ω (ohms)
measured with- ohmmeter
represented by the variable- R
fuse
a fuse is part of a circuit. it breaks the circuit if there is too much current, but it must be replaced.
short circuit
a circuit that has a path for electrons to flow, but has no load, so it is very dangerous.
series circuit
a circuit that only has one path for electrons to flow. the electrical devices share the electrical energy. voltage is shared, current stays the same. if one part of the circuit stops working, the rest will stop working.
parallel circuit
electrons have more than one path to flow. electrical devices do not share electrical energy. voltage is the same, current is shared. if one device stops working, the rest will not turn off.
Ohm’s Law
describes the relationship between voltage, current, and resistance in an electrical circuit.
current
the amount of charge (amount of electrons) that pass through a wire per unit of time (seconds)
